21、SSM框架 |
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21、SSM框架
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本文要实现Mybatis多参数查询与列表查询不同方式实现，以一个实例来说明。 本文示例工程下载 一、查询所有数据，返回List 查询出列表，也就是返回list, 在我们这个例子中也就是 List , 这种方式返回数据，需要在Employeer.xml 里面配置返回的类型 resultMap, 注意不是 resultType, 而这个resultMap 所对应的应该是我们自己配置的 [html] view plain copy print ?
id、result是最简单的映射，id为主键映射；result其他基本数据库表字段到实体类属性的映射。
查询列表的语句在 Employeer.xml 中 [html] view plain copy print ?
select * from `t_employeer` where employeer_name like #{employeer_name}
select * from `t_employeer` where employeer_name like #{employeer_name}
在EmployeerMapper 接口中增加方法：public List findEmployeerByName(String employeer_name);
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/** * 注意要和Employeer.xml的方法名对应 */ public List findEmployeerByName(String employeer_name);
/**
* 注意要和Employeer.xml的方法名对应
*/
public List findEmployeerByName(String employeer_name);
测试：
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/** * 查询列表 */ public static List getEmployeerList(String employeer_name){ SqlSession session = null; List employeers=null; try { session = sqlSessionFactory.openSession(); EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class); employeers = employeerMapper.findEmployeerByName(employeer_name); session.commit() ; } finally { session.close(); } return employeers; } public static void main(String[] args) { List employeers=getEmployeerList("张三"); for(Employeer employeer:employeers){ System.out.println(employeer); } }
/**
* 查询列表
*/
public static List getEmployeerList(String employeer_name){
SqlSession session = null;
List employeers=null;
try {
session = sqlSessionFactory.openSession();
EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class);
employeers = employeerMapper.findEmployeerByName(employeer_name);
session.commit() ;
} finally {
session.close();
}
return employeers;
}
public static void main(String[] args) {
List employeers=getEmployeerList("张三");
for(Employeer employeer:employeers){
System.out.println(employeer);
}
}
结果：
其中的数据的之前插入的，现在要查找张三的列表全部都列出来了。 二、多参数查询 （1）方法一 EmployeerMapper中定义 [java] view plain copy print ?
/** * 多参数查询，注意要和Employeer.xml的方法名对应 */ public List findEmployeerByNameandDep(String employeer_name,String employeer_department);
/**
* 多参数查询，注意要和Employeer.xml的方法名对应
*/
public List findEmployeerByNameandDep(String employeer_name,String employeer_department);Employeer.xml中定义
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select* from `t_employeer` where employeer_name=#{0} and employeer_department=#{1}
select* from `t_employeer` where employeer_name=#{0} and employeer_department=#{1}
由于是多参数那么就不能使用parameterType， 改用#｛index｝是第几个就用第几个的索引，索引从0开始
测试代码： [java] view plain copy print ?
/** * 多参数查询列表 */ public static List getEmployeerList(String employeer_name,String employeer_department){ SqlSession session = null; List employeers=null; try { session = sqlSessionFactory.openSession(); EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class); employeers = employeerMapper.findEmployeerByNameandDep(employeer_name, employeer_department); session.commit() ; } finally { session.close(); } return employeers; }
/**
* 多参数查询列表
*/
public static List getEmployeerList(String employeer_name,String employeer_department){
SqlSession session = null;
List employeers=null;
try {
session = sqlSessionFactory.openSession();
EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class);
employeers = employeerMapper.findEmployeerByNameandDep(employeer_name, employeer_department);
session.commit() ;
} finally {
session.close();
}
return employeers;
}
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public static void main(String[] args) { System.out.println("=========================使用多单参数查询==========================="); List employeers1=getEmployeerList("张三","产品二部"); for(Employeer employeer1:employeers1){ System.out.println(employeer1); }
public static void main(String[] args) {
System.out.println("=========================使用多单参数查询===========================");
List employeers1=getEmployeerList("张三","产品二部");
for(Employeer employeer1:employeers1){
System.out.println(employeer1);
}
结果：
方法二： 将 resultMap="resultMap" 改成 resultType="Employeer" [java] view plain copy print ?
select* from `t_employeer` where employeer_name=#{0} and employeer_department=#{1}
select* from `t_employeer` where employeer_name=#{0} and employeer_department=#{1}
方法三：Map封装多参数
EmployeerMapper.java中添加
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/** * 多参数查询，注意要和Employeer.xml的方法名对应 */ public List findEmployeerByNameandDep1(Map map);
/**
* 多参数查询，注意要和Employeer.xml的方法名对应
*/
public List findEmployeerByNameandDep1(Map map);Employeer.xml中添加：
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select* from `t_employeer` where employeer_name=#{key1} and employeer_department=#{key2}
select* from `t_employeer` where employeer_name=#{key1} and employeer_department=#{key2}
其中map是mybatis自己配置好的直接使用就行。map中key的名字是那个就在#{}使用那个。
测试使用： [java] view plain copy print ?
/** * 多参数查询列表，使用map */ public static List getEmployeerList(Map map){ SqlSession session = null; List employeers=null; try { session = sqlSessionFactory.openSession(); EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class); employeers = employeerMapper.findEmployeerByNameandDep1(map); session.commit() ; } finally { session.close(); } return employeers; }
/**
* 多参数查询列表，使用map
*/
public static List getEmployeerList(Map map){
SqlSession session = null;
List employeers=null;
try {
session = sqlSessionFactory.openSession();
EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class);
employeers = employeerMapper.findEmployeerByNameandDep1(map);
session.commit() ;
} finally {
session.close();
}
return employeers;
}
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System.out.println("=========================使用多单参数map方式查询==========================="); Map map = new HashMap(); map.put("key1", "明明"); map.put("key2", "财会部"); List employeers2=getEmployeerList(map); for(Employeer employeer2:employeers2){ System.out.println(employeer2); }
System.out.println("=========================使用多单参数map方式查询===========================");
Map map = new HashMap();
map.put("key1", "明明");
map.put("key2", "财会部");
List employeers2=getEmployeerList(map);
for(Employeer employeer2:employeers2){
System.out.println(employeer2);
}
一定要注意key:
结果：
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