到看這里，現在在返回第一章，hibernate 和 mybatis的區別，是否感覺更加深刻了。
下面我們進入我們本章的重點： mybatis 實際應用中按照下面的4個步驟： - 創建實體對象 （User.java） - 創建操作數據庫接口 (UserDao.java) - 用mapper 完成接口實現 （UserDao.xml） 重點（通過mapper 映射就可以直接調用接口） - 配置映射文件包（在mybatis-config.xml中配置）
下面是代碼： 
User.java 代碼
package com.zll.mybatis.bean;import java.util.Date;public class User { PRivate int id; private int parentId; private int sonId; private String name; private Date birthday; public int getId() { return id; } public void setId(int id) { this.id = id; } public int getParentId() { return parentId; } public void setParentId(int parentId) { this.parentId = parentId; } public int getSonId() { return sonId; } public void setSonId(int sonId) { this.sonId = sonId; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } @Override public String toString() { return "User [id=" + id + ", parentId=" + parentId + ", sonId=" + sonId + ", name=" + name + ", birthday=" + birthday + "]"; }}UserDao 代碼
package com.zll.mybatis.dao;import java.util.List;import com.zll.mybatis.bean.User;public interface UserDao { public void insertReteunId(User user) throws Exception; public void deleteById(int id) throws Exception; public void updateById(User user) throws Exception; public List<User> findByName(String username) throws Exception;}這里必須做到4個一致： 1、namespace 和 映射對象 包名類名一致。 2、id名稱 和 映射對象 方法名 一致 3、parameterType 和 映射對象 參數類型 一致 4、resultType 和 映射對象 返回類型 一致
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.zll.mybatis.dao.UserDao"> <!-- 增加用戶并返回 id--> <insert id="insertReteunId" parameterType="com.zll.mybatis.bean.User"> <selectKey keyProperty="id" order="AFTER" resultType="int"> <!-- sql語句，獲取最近插入數據的id --> select last_insert_id(); </selectKey> insert into user(parentId,sonId,name,birthday) value(#{parentId},#{sonId},#{name},#{birthday}) </insert> <!-- 刪除 --> <delete id="deleteById" parameterType="int"> delete from user where id=#{id} </delete> <!-- 更新 --> <update id="updateById" parameterType="com.zll.mybatis.bean.User"> update user set parentId=#{parentId},sonId=#{sonId},name=#{name},birthday=#{birthday} where id=#{id} </update> <!-- 模糊查詢 ${}符號表示sql使用拼接方式，這樣會參數sql注入露點，所以大家要注意 --> <select id="findByName" parameterType="string" resultType="com.zll.mybatis.bean.User"> <!-- select * from user where name like "%${value}%" --> select * from user where name like #{value} </select></mapper>最后在在mybatis-config.xml中添加映射路徑：
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="com.MySQL.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/my_db?characterEncoding=UTF8"/> <property name="username" value="root"/> <property name="passWord" value="root"/> </dataSource> </environment> </environments> <mappers> <!-- 映射路徑 添加整個包，就不用每個類都配置了 --> <package name="com/zll/mybatis/dao"/> </mappers></configuration>測試代碼（直接調用接口完成數據查詢）：
package com.zll.mybatis.mybatis;import java.io.InputStream;import java.util.Date;import java.util.List;import junit.framework.TestCase;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import com.zll.mybatis.bean.User;import com.zll.mybatis.dao.UserDao;/** * Unit test for simple App. */public class APPTest extends TestCase { SqlSessionFactory sqlSessionFactory; @Override protected void setUp() throws Exception { super.setUp(); String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } public void insertUser() throws Exception { SqlSession session = sqlSessionFactory.openSession(); UserDao mapper = session.getMapper(UserDao.class); User user = new User(); user.setName("小紅蘿卜"); user.setBirthday(new Date()); mapper.insertReteunId(user); System.out.println("user id = "+user.getId()); session.close(); } public void updateUser() throws Exception { SqlSession session = sqlSessionFactory.openSession(); UserDao mapper = session.getMapper(UserDao.class); User user = new User(); user.setId(4); user.setParentId(3); user.setName("小狗蛋"); user.setBirthday(new Date()); mapper.updateById(user); session.commit(); session.close(); } public void findUser() throws Exception { SqlSession session = sqlSessionFactory.openSession(); UserDao mapper = session.getMapper(UserDao.class); List<User> list = mapper.findByName("%小%"); for(int i=0; i<list.size(); i++){ System.out.println(list.get(i)); } session.close(); } public void deleteUser() throws Exception { SqlSession session = sqlSessionFactory.openSession(); UserDao mapper = session.getMapper(UserDao.class); mapper.deleteById(8); session.commit(); session.close(); }}新聞熱點
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