自定义StringBuilder类拼接非空字符串

Posted 2021-02-04 coloz

主要目的: 为了拼接多个非空字符串,还能达到链式的装X效果
这里不考虑线程安全,所以使用StringBuilder快速拼接非空内容,中间用","作为分隔。

代码如下:

package com.baidu;
import org.apache.commons.lang.StringUtils;
import org.junit.Test;

public class MyStringBuilder {
    private StringBuilder sb;
    private Thread thread;
    public MyStringBuilder() {
        this.thread = Thread.currentThread ();
        //判断放在放在构造函数中
        if (sb == null) {
            sb = new StringBuilder ();
        }
    }

    public StringBuilder getSb() {
        return sb;
    }

    public MyStringBuilder setSb(StringBuilder sb) {
        this.sb = sb;
        return this;
    }

    //item为空不拼接
    public MyStringBuilder append(String item) {
        if (this.thread != Thread.currentThread ()) {
            throw new RuntimeException ("不能在多线程中使用");
        }

        if (StringUtils.isNotBlank (item)) {
            if (sb.length () > 0) {
                sb.append (",");
            }
            sb.append (item);
        }
        return this;
    }

    //不暴漏get方法,直接用类实例toString()
    public String toString() {
        //清空缓存并返回sb里的数据
        String var1 = sb.toString ();
        sb.delete (0, sb.length ());
        return var1;
    }

    @Test
    public void test() {
        MyStringBuilder mySb = new MyStringBuilder ();
        mySb.append ("aaa").append ("bbb").append ("ccc");
        System.out.println ("mySb :" + mySb.toString ());

        MyStringBuilder mySb2 = new MyStringBuilder ();
        mySb2.append ("aaa2")
                .append ("bbb2")
                .append ("ccc2");
        System.out.println ("mySb2 :" + mySb2.toString ());

        //测试不能再多线程使用异常
        new Thread (() -> {
            mySb.append ("rr");
        }).start ();
    }
}