Apache DBUtils用法

Posted 2020-12-11 亲爸爸

1.所需的jar包

https://mvnrepository.com/artifact/commons-dbutils/commons-dbutils

 

2.重点类/接口

• QueryRunner: 实现增删查改操作
• ResultSetHandler:接口;实现类返回结果/结果类型

3.增删查改

/**
         * 查询单行数据,用数组接收
         * 条件有多个满足,例如>?,也只会读取一行
         */
        QueryRunner qr = new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        Object[] user = qr.query("select * from student where id =?", new ArrayHandler(), 3);
        System.out.println("查询单行数据,用数组接收:" + user[0] + "---" + user[1]);

/**
         * 查询单值结果,即条件下列的值
         */
        QueryRunner qr6 = new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        Integer a = qr.query("SELECT money FROM student WHERE id = ?", new ScalarHandler<Integer>(), 1);
        System.out.println("查询单值结果,即条件下列的值:"+a);

 

 /**
         * 查询多行数据,用集合接收
         */
        QueryRunner qr1 = new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        List<Object[]> user1 = qr.query("select * from student", new ArrayListHandler());
        System.out.println("查询多行数据,用集合接收:");
        for (Object[] s : user1)
            System.out.println(s[0] + "---" + s[1]);

 /**
         *查询单行数据,用对象接收
         */
        QueryRunner qr2 = new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        Student student = qr2.query("select * from student where id > ?", new BeanHandler<Student>(Student.class), 1);
        System.out.println("查询单行数据:" + student.getId() + "---" + student.getMoney());

/**
         * 查多行数据,用对象集合接收
         */
        QueryRunner qr3 = new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        List<Student> students = qr3.query("select * from student where id > ?", new BeanListHandler<Student>(Student.class), 1);
        System.out.println("查多行数据,用对象集合接收:");
        for (Student s : students) {
            System.out.println(s.getId() + "---" + s.getMoney());
        }

/**
         *查询数据,用map接收
         */
        QueryRunner qr11 = new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        Map<Integer, Student> id = qr.query("select * from student where id > ?", new BeanMapHandler<Integer, Student>(Student.class, "id"), 1);
        System.out.println("查询数据,用map接收:");
        for (Integer integer : id.keySet()) {
            Student student1 = id.get(integer);
            System.out.println(student1.getId()+"---"+student1.getMoney());
        }

 /**
         *查询数据,以id为key值,对象为value值
         */
        QueryRunner qr4 = new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        Map<Integer, Map<String, Object>> s = qr4.query("select * from student where id > ?", new KeyedHandler<Integer>(), 1);
        System.out.println("student对象取值:" + s + ",key为2的对象值:" + s.get(2));

/**
         *得到满足条件的列id
         */
        QueryRunner qr5 = new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        List<Integer> ss = qr5.query("select * from student where id > ?", new ColumnListHandler<Integer>("id"), 1);
        System.out.println("得到满足条件的列id");
        for (Integer s0 : ss) {
            System.out.println(s0);
        }

/**
         * 多条件查询,new Object[]{----}
         */
        QueryRunner qr7= new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        Integer b = qr.query("SELECT money FROM student WHERE id = ? and money like ?", new ScalarHandler<Integer>(), new Object[]{1, "%0%"});
        System.out.println("多条件查询:"+b);

　　

 /**
         * 增
         */
        QueryRunner qr8= new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        int count = qr.update("insert into student (money)  values (?)", 500);
        System.out.println("增加了" + count + "条数据");

 /**
         * 改
         */
        QueryRunner qr9= new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        int count1 = qr.update("update student set money=? where id=?", new Object[]{500,5});
        System.out.println("修改了" + count1 + "条数据");

 /**
         * 删
         */
        QueryRunner qr10= new QueryRunner(ComboPooledDataSourceUtil.getDataSourceByxml());
        int count2 = qr.update("delete from student  where id=?", 4);
        System.out.println("删除了" + count2 + "条数据");

 

注释:数据源 c3p0