XUtils使用

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定义实体

public abstract class EntityBase {
//@Id // 如果主键没有命名名为id或_id的时，需要为主键添加此注解
//@NoAutoIncrement // int,long类型的id默认自增，不想使用自增时添加此注解
private int id;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}

数据库表创建

@Table(name = "autoForm", execAfterTableCreated = "CREATE UNIQUE INDEX index_autoForm_url ON autoForm(url)")
public class AutoForm extends EntityBase {
@Column(column = "url")
private String url;
@Column(column = "content")
private String content;

public String getUrl() {
return url;
}

.....

}

一些常用方法借鉴部分

DbUtils db = DbUtils.create(this);
User user = new User(); //这里需要注意的是User对象必须有id属性，或者有通过@ID注解的属性
user.setEmail("wyouflf@qq.com");
user.setName("wyouflf");
db.save(user); // 使用saveBindingId保存实体时会为实体的id赋值
...
// 查找
Parent entity = db.findById(Parent.class, parent.getId());
List<Parent> list = db.findAll(Parent.class);//通过类型查找
Parent Parent = db.findFirst(Selector.from(Parent.class).where("name","=","test"));
// IS NULL
Parent Parent = db.findFirst(Selector.from(Parent.class).where("name","=", null));
// IS NOT NULL
Parent Parent = db.findFirst(Selector.from(Parent.class).where("name","!=", null));
// WHERE id<54 AND (age>20 OR age<30) ORDER BY id LIMIT pageSize OFFSET pageOffset
List<Parent> list = db.findAll(Selector.from(Parent.class)
.where("id" ,"<", 54)
.and(WhereBuilder.b("age", ">", 20).or("age", " < ", 30))
.orderBy("id")
.limit(pageSize)
.offset(pageSize * pageIndex));
// op为"in"时，最后一个参数必须是数组或Iterable的实现类(例如List等)
Parent test = db.findFirst(Selector.from(Parent.class).where("id", "in", new int[]{1, 2, 3}));
// op为"between"时，最后一个参数必须是数组或Iterable的实现类(例如List等)
Parent test = db.findFirst(Selector.from(Parent.class).where("id", "between", new String[]{"1", "5"}));
DbModel dbModel = db.findDbModelAll(Selector.from(Parent.class).select("name"));//select("name")只取出name列
List<DbModel> dbModels = db.findDbModelAll(Selector.from(Parent.class).groupBy("name").select("name", "count(name)"));
...
//例：分组聚合查询出 Parent表中非重复的name和它的对应数量
List<DbModel> dbModels = db.findDbModelAll(Selector.form(Parent.class).select("distinct name,count(name) as num").groupBy("name"));
db.execNonQuery("sql") // 执行自定义sql

转载部分 http://www.bubuko.com/infodetail-801946.html

（3）常见数据库操作

1）查询

DbUtils db = DbUtils.create(this);
List<Grade> stus = db.findAll(Selector.from(Grade.class).where("class_name", "=", ""));
List<Student>list = db.findAll(Selector.from(Student.class)
.where("id","<", 34)
.and(WhereBuilder.b("age",">", 15).or("age", " < ", 20))
.orderBy("id")
.limit(pageSize)
.offset(pageSize* pageIndex));

Studenttest = db.findFirst(Selector.from(Student.class).where("id","in", new int[]{1, 2, 3}));
Studenttest = db.findFirst(Selector.from(Student.class).where("id","between", new String[]{"2", "5"}));
DbModeldbModel =db.findDbModelAll(Selector.from(Student.class).select("name"));//select("name")只取出name列
List<DbModel>dbModels =db.findDbModelAll(Selector.from(Student.class).groupBy("name").select("name","count(name)"));

2）自定义查询（常用到的链接查询可以这样写）

SqlInfo sqlInfo = new SqlInfo();
sqlInfo.setSql("select * from tbl_Student a,tbl_class b where a.stu_class_id = b.id and a.id > ?");
sqlInfo.addBindArg(2);
List<DbModel> StudentByInfo = db.findDbModelAll(sqlInfo);

3）删除，包含三种方法：删除list集合，根据Id删除，删除一个对象

List<Grade> stus = db.findAll(Selector.from(Grade.class).where("class_name", "=", ""));
db.deleteAll(stus);

db.deleteById(Grade.class, 2);

db.delete(stus.get(3));

4）更新操作和删除操作类似，这里就一一列举

四、有关xUtils

开源项目地址以及作者：https://github.com/wyouflf/xUtils

xUtils api地址
http://xutilsapi.oschina.mopaas.com/

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