喜剧演员，兼开发工程师(github.com/qiuyongchen)

Run -> Edit Configurations -> 左上角’+’号 -> Tomcat -> Local -> Deployment -> 中间’+’号 -> Artific -> 选择后面附带war exploded的那项 -> 点击OK

package com.iloveqyc.web;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/3
 * Time: 下午2:57
 * Usage: xxx
 */
public class testServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("hello");
        System.out.println("邱永臣");
        PrintWriter writer = resp.getWriter();
        writer.print("someone who is stupid is coming");
        writer.close();
    }
}

protected void service(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException
{
    String method = req.getMethod();

    if (method.equals(METHOD_GET)) {
        long lastModified = getLastModified(req);
        if (lastModified == -1) {
            // servlet doesn't support if-modified-since, no reason
            // to go through further expensive logic
            doGet(req, resp);
        } else {
            long ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE);
            if (ifModifiedSince < lastModified) {
                // If the servlet mod time is later, call doGet()
                // Round down to the nearest second for a proper compare
                // A ifModifiedSince of -1 will always be less
                maybeSetLastModified(resp, lastModified);
                doGet(req, resp);
            } else {
                resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
            }
        }

    } else if (method.equals(METHOD_HEAD)) {
        long lastModified = getLastModified(req);
        maybeSetLastModified(resp, lastModified);
        doHead(req, resp);

    } else if (method.equals(METHOD_POST)) {
        doPost(req, resp);
        
    } else if (method.equals(METHOD_PUT)) {
        doPut(req, resp);
        
    } else if (method.equals(METHOD_DELETE)) {
        doDelete(req, resp);
        
    } else if (method.equals(METHOD_OPTIONS)) {
        doOptions(req,resp);
        
    } else if (method.equals(METHOD_TRACE)) {
        doTrace(req,resp);
        
    } else {

        String errMsg = lStrings.getString("http.method_not_implemented");
        Object[] errArgs = new Object[1];
        errArgs[0] = method;
        errMsg = MessageFormat.format(errMsg, errArgs);
        
        resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg);
    }
}

package com.iloveqyc.web.servlet;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/3
 * Time: 下午2:57
 * Usage: xxx
 */
public class ResDefaultServlet extends HttpServlet {

    private ServletConfig servletConfig;

    @Override
    public void init(ServletConfig config) throws ServletException {
        servletConfig = config;
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String name = servletConfig.getInitParameter("createdBy");
        System.out.println(name);
        
        System.out.println(this.getClass().toString() + " had been visited");
        PrintWriter writer = resp.getWriter();
        writer.print("the init res servlet");
        writer.close();
    }
}

package com.iloveqyc.web.servlet;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/3
 * Time: 下午2:57
 * Usage: xxx
 */
public class ResDefaultServlet extends HttpServlet {

    private ServletConfig servletConfig;

    @Override
    public void init(ServletConfig config) throws ServletException {
        servletConfig = config;
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String name = servletConfig.getServletContext().getInitParameter("nameOfWebApp");
        System.out.println(name);

        System.out.println(this.getClass().toString() + " had been visited");
        PrintWriter writer = resp.getWriter();
        writer.print("the init res servlet");
        writer.close();
    }
}

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    String name = servletConfig.getServletContext().getInitParameter("nameOfWebApp");
    System.out.println(name);

    System.out.println(this.getClass().toString() + " had been visited");
    PrintWriter writer = resp.getWriter();
    writer.print("the init res servlet");
    writer.close();
}

package com.iloveqyc.web.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/14
 * Time: 下午5:43
 * Usage: xxx
 */
public class TestRequsetServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setCharacterEncoding("UTF-8");

        PrintWriter writer = resp.getWriter();
        writer.println("getAuthType: " + req.getAuthType());
        writer.println("getContextPath: " + req.getContextPath());
        writer.println("getCookies: " + req.getCookies().toString());
        writer.println("getHeaderNames: " + req.getHeaderNames());
        Enumeration<String> headers = req.getHeaderNames();
        writer.println("头部信息如下：");
        while (headers.hasMoreElements()) {
            String header = headers.nextElement();
            writer.println(header + " : " + req.getHeader(header));
        }
        writer.println("以上是头部信息");
        writer.println("getMethod: " + req.getMethod());
        writer.println("getPathInfo: " + req.getPathInfo());
        writer.println("getServletPath: " + req.getServletPath());
        writer.println("getRequestedSessionId: " + req.getRequestedSessionId());
        writer.println("getCharacterEncoding: " + req.getCharacterEncoding());
    }
}

req.getRequestDispatcher("/").forward(req,  resp);

// 设置response的返回格式为UTF-8
response.setCharacterEncoding("UTF-8");
// 从response中获取Writer
PrintWriter out = response.getWriter();
// 控制浏览器输出UTF-8格式的字符串
out.write("<meta http-equiv='content-type' content='text/html;charset=UTF-8'/>");
// 给浏览器传回『邱永臣可爱的邱永臣』
out.write("最可爱的邱永臣");

String filePath = this.getServletContext().getRealPath("test.download");
String fileName = filePath.substring(filePath.indexOf("\\") + 1);
resp.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));

InputStream inputStream = new FileInputStream(filePath);
OutputStream outputStream = resp.getOutputStream();
byte[] buffer = new byte[1024];
int length = 0;
while ((length = inputStream.read(buffer)) > 0) {
    outputStream.write(buffer, 0, length);;
}

inputStream.close();

package com.iloveqyc.web.servlet;

import lombok.extern.slf4j.Slf4j;
import javax.servlet.ServletException;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/13
 * Time: 下午6:27
 * Usage: xxx
 */
@Slf4j
public class TestRedirectServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setStatus(HttpServletResponse.SC_FOUND);
        resp.setHeader("Location", "/");
        
        log.info("redirect now.");
    }
}

/*
 * Generated by the Jasper component of Apache Tomcat
 * Version: Apache Tomcat/7.0.37
 * Generated at: 2017-03-16 03:50:49 UTC
 * Note: The last modified time of this file was set to
 *       the last modified time of the source file after
 *       generation to assist with modification tracking.
 */
package org.apache.jsp;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;

public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase
    implements org.apache.jasper.runtime.JspSourceDependent {

  private static final javax.servlet.jsp.JspFactory _jspxFactory =
          javax.servlet.jsp.JspFactory.getDefaultFactory();

  private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;

  private javax.el.ExpressionFactory _el_expressionfactory;
  private org.apache.tomcat.InstanceManager _jsp_instancemanager;

  public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
    return _jspx_dependants;
  }

  public void _jspInit() {
    _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
    _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
  }

  public void _jspDestroy() {
  }

  public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
        throws java.io.IOException, javax.servlet.ServletException {

    final javax.servlet.jsp.PageContext pageContext;
    javax.servlet.http.HttpSession session = null;
    final javax.servlet.ServletContext application;
    final javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = null;
    final java.lang.Object page = this;
    javax.servlet.jsp.JspWriter _jspx_out = null;
    javax.servlet.jsp.PageContext _jspx_page_context = null;


    try {
      response.setContentType("text/html;charset=UTF-8");
      pageContext = _jspxFactory.getPageContext(this, request, response,
      		    				      null, true, 8192, true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;

      out.write('\n');

    String path = request.getContextPath();
    String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";

      out.write("\n");
      out.write("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">\n");
      out.write("<html>\n");
      out.write("<body>\n");

    out.print("From Jsp");

      out.write("\n");
      out.write("<h2>Hello World!</h2>\n");
      out.write("</body>\n");
      out.write("</html>\n");
    } catch (java.lang.Throwable t) {
      if (!(t instanceof javax.servlet.jsp.SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
          try { out.clearBuffer(); } catch (java.io.IOException e) {}
        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
        else throw new ServletException(t);
      }
    } finally {
      _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }
}

out.print("From Jsp");

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jasper.runtime;

import java.io.IOException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.HttpJspPage;

import org.apache.jasper.compiler.Localizer;

/**
 * This is the super class of all JSP-generated servlets.
 *
 * @author Anil K. Vijendran
 */
public abstract class HttpJspBase extends HttpServlet implements HttpJspPage {
    
    private static final long serialVersionUID = 1L;

    protected HttpJspBase() {
    }

    @Override
    public final void init(ServletConfig config) 
        throws ServletException 
    {
        super.init(config);
        jspInit();
        _jspInit();
    }
    
    @Override
    public String getServletInfo() {
        return Localizer.getMessage("jsp.engine.info");
    }

    @Override
    public final void destroy() {
        jspDestroy();
        _jspDestroy();
    }

    /**
     * Entry point into service.
     */
    @Override
    public final void service(HttpServletRequest request, HttpServletResponse response) 
        throws ServletException, IOException 
    {
        _jspService(request, response);
    }
    
    @Override
    public void jspInit() {
    }

    public void _jspInit() {
    }

    @Override
    public void jspDestroy() {
    }

    protected void _jspDestroy() {
    }

    @Override
    public abstract void _jspService(HttpServletRequest request, 
                                     HttpServletResponse response) 
        throws ServletException, IOException;
}

final javax.servlet.jsp.PageContext pageContext;
javax.servlet.http.HttpSession session = null;
final javax.servlet.ServletContext application;
final javax.servlet.ServletConfig config;
javax.servlet.jsp.JspWriter out = null;
final java.lang.Object page = this;
javax.servlet.jsp.JspWriter _jspx_out = null;
javax.servlet.jsp.PageContext _jspx_page_context = null;

out.print(表达式);

class Index_Jsp extends HttpJspBase {
  int i = 0;
  
  void _jspService() {
    i = i + 1;
    out.print(i);
  }
}

package com.iloveqyc.web.tag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.Tag;
import java.io.IOException;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/17
 * Time: 上午12:20
 * Usage: xxx
 */
public class qycTag implements Tag {
    private PageContext pageContext;

    public void setPageContext(PageContext pageContext) {
        this.pageContext = pageContext;
    }

    public void setParent(Tag tag) {
    }

    public Tag getParent() {
        return null;
    }

    public int doStartTag() throws JspException {
        JspWriter out = pageContext.getOut();
        try {
            out.write("邱永臣自定义的标签");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return 0;
    }

    public int doEndTag() throws JspException {
        return 0;
    }

    public void release() {
    }
}

request.getDispatcher("xxx.jsp").forward(rep, resp);

request.setAttribute("modelValue", "value");
request.getDispatcher("xxx.jsp").forward(rep, resp);

resp.addCookie(new Cookie("qiuyongchen", "handsome man"));

package com.iloveqyc.web.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletResponse;
import javax.servlet.http.*;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/14
 * Time: 下午7:17
 * Usage: xxx
 */
public class TestCookieSessionServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.addCookie(new Cookie("isQiuyongchenHandsome", "yes"));
        resp.setCharacterEncoding("UTF-8");
        PrintWriter writer = resp.getWriter();

        HttpSession session = req.getSession();
        if (session.isNew()) {
            writer.println("session.isNew() : " + session.getId());
        } else {
            writer.println("session.isNotNew() : " + session.getId());
        }

        writer.close();
    }
}

session.setAttribute("myName", "qiuyongchen");
session.getAttribute("myName");

/**
 * Encodes the specified URL by including the session ID,
 * or, if encoding is not needed, returns the URL unchanged.
 * The implementation of this method includes the logic to
 * determine whether the session ID needs to be encoded in the URL.
 * For example, if the browser supports cookies, or session
 * tracking is turned off, URL encoding is unnecessary.
 */

HttpSession session = req.getSession();
writer.println("下面的URL理应附带sessionId");
String url = req.getContextPath() + "/user?name=";
url = resp.encodeURL(url);

package com.iloveqyc.service.Utils;

import sun.misc.BASE64Encoder;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/15
 * Time: 上午11:31
 * Usage: xxx
 */
public class TokenUtils {
    public static String makeToken() {
        String randStr = System.currentTimeMillis() + new Random().nextInt(Integer.MAX_VALUE) + "";
        try {
            // MD5编码
            MessageDigest messageDigest = MessageDigest.getInstance("md5");
            byte[] md5 = messageDigest.digest(randStr.getBytes());
            // BASE64编码
            BASE64Encoder base64Encoder = new BASE64Encoder();
            return base64Encoder.encode(md5);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException();
        }
    }
}

log.info("这是一条测试日志");

package com.iloveqyc.service.SQL;

import java.sql.*;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/17
 * Time: 下午7:12
 * Usage: xxx
 */
public class test1 {
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        
        // 连接数据库，并执行SQL查询
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/resWeb");
        Statement statement = conn.createStatement();
        ResultSet res = statement.executeQuery("SELECT * FROM Name");
        
        // 打印结果
        while (res.next()) {
            System.out.println("Name : " + res.getObject("Name"));
            System.out.println("Id : " + res.getObject("Id"));;
        }

        // 关闭资源
        res.close();
        statement.close();
        conn.close();
    }
}

package com.iloveqyc.service.Utils;

import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/19
 * Time: 下午11:26
 * Usage: xxx
 */
public class SQLUtils {

    public static String driver = null;
    public static String url = null;
    public static String user = null;
    public static String password = null;

    static {
        try {
            InputStream inputStream = SQLUtils.class.getClassLoader().getResourceAsStream("db.properties");
            Properties prop = new Properties();
            prop.load(inputStream);

            // 可见，你可以把Properties当做KV结构体来使用，从中取出key对应的value。
            driver = prop.getProperty("driver");
            url = prop.getProperty("url");
            user = prop.getProperty("user");
            password = prop.getProperty("password");

            Class.forName(driver);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static String getTest() {
        return driver + url + user + password;
    }

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }

    public static void release(Connection conn, Statement st, ResultSet resultSet) {
        try {
            if (resultSet != null) {
                resultSet.close();
                resultSet = null;
            }
            if (st != null) {
                st.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

// C
public void testInsertCreate() throws SQLException {
    Connection conn = SQLUtils.getConnection();
    Statement st = conn.createStatement();
    int row = st.executeUpdate("INSERT INTO `OP_BackCategory` (`ID`, `Name`, `Status`, `AddTime`, `UpdateTime`)\n" +
            "VALUES\n" +
            "\t(12100, '邱永臣品类', 1, '2017-03-17 10:46:52', '2017-03-17 10:46:52');\n");
    System.out.println("插入行数：" + row);
    SQLUtils.release(conn, st, null);
}

// U
public void testUpdate() throws SQLException {
    Connection conn = SQLUtils.getConnection();
    Statement st = conn.createStatement();
    int row = st.executeUpdate("UPDATE OP_BackCategory SET Name = '邱永臣改名' WHERE ID = 12100");
    System.out.println("更改行数：" + row);
    SQLUtils.release(conn, st, null);
}

// R
public void testRetrieve() throws SQLException {
    Connection conn = SQLUtils.getConnection();
    Statement st = conn.createStatement();
    ResultSet res = st.executeQuery("SELECT * FROM OP_BackCategory");
    System.out.println("数据库：");
    while (res.next()) {
        System.out.println(res.getObject("Name"));
    }
    System.out.println();
    SQLUtils.release(conn, st, res);
}

// D
public void testDelet() throws SQLException {
    Connection conn = SQLUtils.getConnection();
    Statement st = conn.createStatement();
    int row = st.executeUpdate("DELETE FROM OP_BackCategory WHERE ID = 12100");
    System.out.println("删除行数：" + row);
    SQLUtils.release(conn, st, null);
}

// C
public void testInsertCreate2() throws SQLException {
    Connection conn = SQLUtils.getConnection();
    PreparedStatement preSt = conn.prepareStatement("INSERT INTO `OP_BackCategory` (`ID`, `Name`, `Status`, `AddTime`, `UpdateTime`)" +
            " VALUES (?, ?, ?, ?, ?)");
    preSt.setInt(1, 12100);
    preSt.setString(2, "邱永臣品类");
    preSt.setInt(3, 1);
    preSt.setDate(4, new Date(new java.util.Date().getTime()));
    preSt.setDate(5, new Date(new java.util.Date().getTime()));
    int row = preSt.executeUpdate();
    System.out.println("插入行数：" + row);
    SQLUtils.release(conn, preSt, null);
}

// U
public void testUpdate2() throws SQLException {
    Connection conn = SQLUtils.getConnection();
    PreparedStatement preSt = conn.prepareStatement("UPDATE OP_BackCategory SET Name = ? WHERE ID = ?");
    preSt.setString(1, "邱永臣又改名");
    preSt.setInt(2, 12100);
    int row = preSt.executeUpdate();
    System.out.println("更改行数：" + row);
    SQLUtils.release(conn, preSt, null);
}

// R
public void testRetrieve2() throws SQLException {
    Connection conn = SQLUtils.getConnection();
    PreparedStatement preSt = conn.prepareStatement("SELECT * FROM OP_BackCategory WHERE ID = ?");
    preSt.setInt(1, 12100);
    ResultSet res = preSt.executeQuery();
    while (res.next()) {
        System.out.println(res.getObject("Name"));
    }
    SQLUtils.release(conn, preSt, res);
}

for (int i = 0; i < 100; i++) {
  preSt.setInt(1, i);
  preSt.addBatch();
}

public void testRollback() throws SQLException {
    Connection conn = SQLUtils.getConnection();
    // 关闭自动提交
    conn.setAutoCommit(false);
    PreparedStatement preSt = conn.prepareStatement("UPDATE OP_BackCategory SET Name = ? WHERE ID = ?");
    preSt.setString(1, "邱永臣第一次改名");
    preSt.setInt(2, 12100);
    
    // 第一次更改数据库
    int row = preSt.executeUpdate();
    System.out.println("更改行数：" + row);

    PreparedStatement preSt2 = conn.prepareStatement("UPDATE OP_BackCategory SET Name = ? WHERE ID = ?");
    preSt2.setString(1, "邱永臣第二次改名");
    preSt2.setInt(2, 12100);
    
    // 第二次更改数据库
    row = preSt2.executeUpdate();
    System.out.println("更改行数：" + row);

    // 提交事务
    conn.commit();

    SQLUtils.release(conn, preSt, null);
}

public void testRollback() {
    Connection conn = null;
    Savepoint savepoint = null;
    PreparedStatement preSt = null;

    try {
        conn = SQLUtils.getConnection();
        // 关闭自动提交
        conn.setAutoCommit(false);

        PreparedStatement preX = conn.prepareStatement("UPDATE OP_BackCategory SET Name = ? WHERE ID = ?");
        preX.setString(1, "邱永臣与创世纪");
        preX.setInt(2, 12100);
        preX.executeUpdate();

        // 设置回滚点
        savepoint = conn.setSavepoint();

        preSt = conn.prepareStatement("UPDATE OP_BackCategory SET Name = ? WHERE ID = ?");
        preSt.setString(1, "邱永臣第一次改名");
        preSt.setInt(2, 12100);
        int row = preSt.executeUpdate();
        System.out.println("更改行数：" + row);

        // 人为抛出异常，后面的"提交事务"无法执行
        int i = 0 / 0;

        PreparedStatement preSt2 = conn.prepareStatement("UPDATE OP_BackCategory SET Name = ? WHERE ID = ?");
        preSt2.setString(1, "邱永臣第二次改名");
        preSt2.setInt(2, 12100);
        row = preSt2.executeUpdate();
        System.out.println("更改行数：" + row);

        // 提交事务
        conn.commit();
        SQLUtils.release(conn, preSt, null);
    } catch (Exception e) {
        System.out.println(e);
        try {
            // 手动回滚到sp，所以不会回滚全部的sql更新
            conn.rollback(savepoint);
            // 再次提交事务，此次提交的事务里，只包含事务开启后到回滚点之间的sql更新
            // 如果不提交，回滚点在连接断开时才起作用，而不是实时起作用
            conn.commit();
        } catch (SQLException e1) {
            e1.printStackTrace();
        }
    }
}

package com.iloveqyc.service.SQL;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections4.CollectionUtils;

import javax.sql.DataSource;
import java.io.PrintWriter;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.LinkedList;
import java.util.Properties;
import java.util.logging.Logger;

/**
 * User: qiuyongchen Nicolas.David
 * Date: 2017/3/22
 * Time: 下午11:47
 * Usage: 简单的数据源
 */
@Slf4j
public class SimpleDataSource implements DataSource {

    // 连接池的具体容器
    private LinkedList<Connection> pool = new LinkedList<Connection>();
    public String driver = null;
    public String url = null;
    public String user = null;
    public String password = null;
    public int initPoolSize = 0;

    public SimpleDataSource(Properties prop) throws ClassNotFoundException {
        driver = prop.getProperty("driver");
        url = prop.getProperty("url");
        user = prop.getProperty("user");
        password = prop.getProperty("password");
        initPoolSize = Integer.valueOf(prop.getProperty("initPoolSize"));

        Class.forName(driver);

        for (int i = 0; i < initPoolSize; i++) {
            try {
                Connection conn = getNewConnection();
                pool.add(conn);
                log.info("init pool: create connection success, conn: {}", conn);
            } catch (SQLException e) {
                log.error("init pool: create new connection fail", e);
            }
        }
        log.info("the size of pool: {}", pool.size());
    }

    private Connection getNewConnection() throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }

    /**
     * <p>Attempts to establish a connection with the data source that
     * this <code>DataSource</code> object represents.
     *
     * @return a connection to the data source
     * @throws SQLException if a database access error occurs
     */
    public Connection getConnection() throws SQLException {
        if (CollectionUtils.isNotEmpty(pool)) {
            final Connection conn = pool.removeLast();
            log.info("will return a connection from pool, conn: {}", conn);

            // 创建代理对象需要：
            // 1.类加载器
            // 2.对象的接口
            // 3.对象调用的handle方法
            return (Connection) Proxy.newProxyInstance(SimpleDataSource.class.getClassLoader(),
                    new Class[]{Connection.class}, new InvocationHandler() {

                        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                            // 如果吃瓜群众调用了Connection.close()方法，则把连接归还给池
                            if (method.getName().equals("close")) {
                                pool.addFirst(conn);
                                log.info("connection.close() is invoked, conn: {}, the size of pool: {}",
                                        conn, pool.size());
                                return null;
                            }
                            log.info("invoke other method: ({}) of conn: {}, the size fo pool: {}",
                                    method.getName(), conn, pool.size());
                            return method.invoke(conn, args);
                        }
                    });
        } else {
            log.error("pool is empty, get new connection for you");
            return getNewConnection();
        }
    }

    public Connection getConnection(String username, String password) throws SQLException {
        return null;
    }
    public <T> T unwrap(Class<T> iface) throws SQLException {
        return null;
    }
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return false;
    }
    public PrintWriter getLogWriter() throws SQLException {
        return null;
    }
    public void setLogWriter(PrintWriter out) throws SQLException {
    }
    public int getLoginTimeout() throws SQLException {
        return 0;
    }
    public void setLoginTimeout(int seconds) throws SQLException {
    }
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return null;
    }
}