mysql主从复制配置见: http://www.blogjava.net/howard-he/

项目中使用mysql 主从复制，但是用程序实现的读写分离，代码片段如下：

1 public DataSource getDataSource(MethodType methodType) {
2 if (methodType == MethodType.WRITE) {
3 return getDataSource(MasterDataSources);
4 } else {
5 return getDataSource(SlaveDataSources);
6 }
7 }

获取数据源，首先你要确定MethodType 类型，一个是读，一个是写

1public enum MethodType {
2 READ, WRITE
3}

读是获取从库数据源，写是获取主库数据源。

这样，就需要在jdbc配置配置两个数据源（一主一从）

还有另一种实现方式，不用程序来控制。mysql 驱动包提供相应的实现 com.mysql.jdbc.ReplicationDriver.
我写了一个简单的例子：

1package com.howard.loadbalance;
2
3import java.sql.Connection;
4import java.sql.ResultSet;
5import java.sql.SQLException;
6import java.sql.Statement;
7import java.util.Properties;
8import java.util.concurrent.ExecutorService;
9import java.util.concurrent.Executors;
10
11import org.slf4j.Logger;
12import org.slf4j.LoggerFactory;
13
14import com.mysql.jdbc.ReplicationDriver;
15
16public class MysqlTest {
17
18 public static class QueryRunnable implements Runnable {
19
20 protected final static Logger logger = LoggerFactory
21 .getLogger(QueryRunnable.class);
22
23 @Override
24 public void run() {
25 logger.info("user size: " + this.query());
26 }
27
28 public int query() {
29 int count = 0;
30 try {
31 ReplicationDriver driver = new ReplicationDriver();
32 Properties props = new Properties();
33 props.put("roundRobinLoadBalance", "true");
34 props.put("autoReconnect", "true");
35 props.put("user", "core");
36 props.put("password", "core");
37 Connection conn = null;
38 Statement stat = null;
39 ResultSet res = null;
40 try {
41 conn = driver
42 .connect(
43 //注意url串中间不要有空格，因为mysql源码对多个地址split时没有trim.
44 "jdbc:mysql:replication://127.0.0.1:3309,127.0.0.1:3306/core",
45 props);
46 //读写分离标记
47 //当设置true时，只会在从库查询数据
48 //当设置false时，会在主库做更新删除操作
49// conn.setReadOnly(true);
50 stat = conn.createStatement();
51 res = stat.executeQuery("select count(1) from c_user");
52 while (res.next())
53 count = res.getInt(1);
54 } finally {
55 if (res != null)
56 res.close();
57 if (stat != null)
58 stat.close();
59 if (conn != null)
60 conn.close();
61 }
62 } catch (SQLException e) {
63 e.printStackTrace();
64 }
65 return count;
66 }
67 }
68
69 public static void main(String[] args) {
70 // 创建线程池测试负载军衡
71 ExecutorService service = Executors.newCachedThreadPool();
72 for (int i = 0; i < 10; i++) {
73 service.execute(new QueryRunnable());
74 }
75 service.shutdown();
76 }
77
78}
79