Mapper method 'x.x.x.x.addUser' has an unsupported return type

dao层代码

public interface UserMapper {
    Integer addUser(User user);
}

测试代码

@Test
public void fun1(){
    SqlSession sqlSession = build.openSession();
    UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    User user = new User();
    user.setName("小明");
    user.setAddress("上海");
    user.setBalance(10000);

    try {
        Integer user1 = userMapper.addUser(user);
        sqlSession.commit();
        System.out.println(user1);
    } catch (Exception e) {
        e.printStackTrace();
        sqlSession.rollback();
    }
}

刚接触mybatis发现在添加数据的时候抛出一个异常，

org.apache.ibatis.binding.BindingException: Mapper method 'com.hd.mapper.UserMapper.addUser' has an unsupported return type: class com.hd.entity.User
	at org.apache.ibatis.binding.MapperMethod.rowCountResult(MapperMethod.java:109)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:57)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)
	at com.sun.proxy.$Proxy6.addUser(Unknown Source)
	at com.hd.mapper.Demo.fun1(Demo.java:47)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

纠缠了半个小时，终于发现原来这里的错误，原来这里是不需要返回类型的，默认的都是返回的int，或者可以修改成Integer类型。