log4j:WARN No appenders could be found for logger (org.apache.ibatis.logging.LogFactory).log4j:WARN Please initialize the log4j system properly.log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException:?### Error querying database. ?Cause: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.imoc.pojo.User with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.imoc.pojo.User.<init>()### The error may exist in com/imoc/mapping/userManpper.xml### The error may involve com/imoc/mapping/userManpper.getUser-Inline### The error occurred while setting parameters### SQL: select * from users where id=?### Cause: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.imoc.pojo.User with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.imoc.pojo.User.<init>() at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:23) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:107) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:98) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:62) at com.imoc.test.Test.main(Test.java:24)Caused by: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.imoc.pojo.User with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.imoc.pojo.User.<init>() at org.apache.ibatis.reflection.factory.DefaultObjectFactory.instantiateClass(DefaultObjectFactory.java:83) at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:45) at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:38) at org.apache.ibatis.executor.resultset.FastResultSetHandler.createResultObject(FastResultSetHandler.java:386) at org.apache.ibatis.executor.resultset.FastResultSetHandler.createResultObject(FastResultSetHandler.java:365) at org.apache.ibatis.executor.resultset.FastResultSetHandler.getRowValue(FastResultSetHandler.java:261) at org.apache.ibatis.executor.resultset.FastResultSetHandler.handleRowValues(FastResultSetHandler.java:216) at org.apache.ibatis.executor.resultset.FastResultSetHandler.handleResultSet(FastResultSetHandler.java:188) at org.apache.ibatis.executor.resultset.FastResultSetHandler.handleResultSets(FastResultSetHandler.java:154) at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:57) at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:70) at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:57) at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:259) at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:132) at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:105) at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:81) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:104) ... 3 moreCaused by: java.lang.NoSuchMethodException: com.imoc.pojo.User.<init>() at java.lang.Class.getConstructor0(Class.java:2849) at java.lang.Class.getDeclaredConstructor(Class.java:2053) at org.apache.ibatis.reflection.factory.DefaultObjectFactory.instantiateClass(DefaultObjectFactory.java:57) ... 19 morepackage?com.imoc.pojo;
public?class?User?{
private?int?id;
????private?String?name;
????private?int?age;
????
public?int?getId()?{
return?id;
}
public?void?setId(int?id)?{
this.id?=?id;
}
public?String?getName()?{
return?name;
}
public?void?setName(String?name)?{
this.name?=?name;
}
public?int?getAge()?{
return?age;
}
public?void?setAge(int?age)?{
this.age?=?age;
}
public?User(int?id)?{
super();
this.id?=?id;
}
public?User(int?id,?String?name,?int?age)?{
super();
this.id?=?id;
this.name?=?name;
this.age?=?age;
}
@Override
public?String?toString()?{
return?"User?[id="?+?id?+?",?name="?+?name?+?",?age="?+?age?+?"]";
}
}<mapper?namespace="com/imoc/mapping/userManpper">
??
????<select?id="getUser"?parameterType="int"?
????????resultType="com.imoc.pojo.User">
?????????select?*?from?users?where?id=#{id}
????</select>
</mapper><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/mybatis"?/>
?????????????????<property?name="username"?value="root"?/>
?????????????????<property?name="password"?value=""?/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper?resource="com/imoc/mapping/userManpper.xml"/>
</mappers>
</configuration> String?resource?=?"config.xml";
InputStream?is=Test.class.getClassLoader().getResourceAsStream(resource);
SqlSessionFactory?sFactory=new?SqlSessionFactoryBuilder().build(is);
SqlSession?sqlSession=sFactory.openSession();
User?user=sqlSession.selectOne("com/imoc/mapping/userManpper.getUser",1);
System.out.println(user);
sqlSession.close();
1 回答
-
玄鑒namespace="com/imoc/mapping/userManpper" 這里原來我寫的就是<mapper namespace="com.imoc.mapping.userManpper">在測試類里面User user=sqlSession.selectOne("com/imoc/mapping/userManpper.getUser",1);是String statement ="com.imoc.mapping.userManpper.getUser"; User user=sqlSession.selectOne(statement,1);可是包同樣的錯誤，所以修改如上。兩者沒區(qū)別
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