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关于数据库查询的问题 最近在自学--------到数据库这块 问题描述,查询完之后其它都没问题就是name赋值为null 如图所示: [Love [nameString=null, age=12, id=1, grade=1], Love [nameString=null, age=28, id=2, grade=2] 下面是各种代码 public <T> List<T> getforList(Class<T> clazz,String sql,Object...args) { Connection connection=null; PreparedStatement preparedStatement=null; ResultSet resultSet=null; List<T> list=null; try { connection=Tools.getConnection(); list=new ArrayList<>(); preparedStatement=(PreparedStatement) connection.prepareStatement(sql); for(int i=0;i<args.length;i++){ preparedStatement.setObject(i+1, args[i]); } List<Map<String , Object>> list2=new ArrayList(); resultSet=(ResultSet) preparedStatement.executeQuery(); ResultSetMetaData rsmdData=(ResultSetMetaData) resultSet.getMetaData(); Map<String , Object> map=null; while(resultSet.next()){ map=new HashMap<>(); for(int i=0;i<rsmdData.getColumnCount();i++){ String nameString=rsmdData.getColumnLabel(i+1); Object valueObject=resultSet.getObject(i+1); map.put(nameString, valueObject); } list2.add(map); } if(list2.size()>0){ T beanObject=null; for(Map<String, Object> m:list2){ beanObject=clazz.newInstance(); for(Map.Entry<String, Object> entry:m.entrySet()){ String nameString=entry.getKey(); Object valueObject=entry.getValue(); BeanUtils.setProperty(beanObject, nameString, valueObject); } list.add(beanObject); } } } catch (Exception e) { e.printStackTrace(); }finally{ Tools.release(connection, preparedStatement, resultSet, null); } return list; } } 这是个查询方法: 测试方法 @Test public void testGetAll() throws Exception { Dao dao=new Dao(); String sqlString="select L_Name name,L_age age ,id,grade from love "; List<Love> list=dao.getforList(Love.class, sqlString); System.out.println(list); } 这个是类 package com.test; public class Love { String name=null; int age; int id; int grade; public String getNameString() { return name; } public void setNameString(String nameString) { this.name = nameString; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public int getId() { return id; } public void setId(int id) { this.id = id; } public int getGrade() { return grade; } public void setGrade(int grade) { this.grade = grade; } @Override public String toString() { return "Love [nameString=" + name + ", age=" + age + ", id=" + id + ", grade=" + grade + "]"; } private Love(String name, int age, int id, int grade) { super(); this.name = name; this.age = age; this.id = id; this.grade = grade; } public Love(){ } }
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