实体类自动重写toString(),equals()和hashCode()方法，tostringhashcode

实体类自动重写toString(),equals()和hashCode()方法，tostringhashcode

编写web项目时会遇到大量的实体类，那么多的实体类都要重写toString(),equals()和hashCode()方法，造成大量重复代码。

解决方法：

1.编写一个抽象类，在类中重写以上三个方法。

2.让实体类继承这个抽象类。

所用jar包：

apache-commons-lang.jar

例子程序：

Model.java抽象类

package justest;

import java.io.Serializable;

import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;
import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

public abstract class Model implements Serializable {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public int hashCode() {
		return HashCodeBuilder.reflectionHashCode(this);
	}

	public String toString() {
		return ToStringBuilder.reflectionToString(this, ToStringStyle.SHORT_PREFIX_STYLE);
	}

	public boolean equals(Object obj) {
		return EqualsBuilder.reflectionEquals(this, obj);
	}
}

Student.java实体类

package justest;

public class Student extends Model {
	
	private static final long serialVersionUID = 1L;
	
	private Long id;
	private String name;
	
	public Student(Long id, String name) {
		super();
		this.id = id;
		this.name = name;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Long getId() {
		return id;
	}	
}

AutoOverride3Method.java测试类

package justest;

public class AutoOverride3Method {
	public static void main(String[] args) {
		Student s1 = new Student(1L, "张三");
		Student s2 = new Student(2L, "李四");
		Student s3 = new Student(1L, "张三");
		
		//测试toString()方法
		System.out.println(s1);
		
		//测试equals方法
		System.out.println(s1.equals(s2));
		System.out.println(s1.equals(s3));
	}

}

输出：

Student[id=1,name=张三]
false
true