JDK源码学习与分析之StringBuilder

        本文基于JDK1.8学习与分析StringBuilder源码。

public final class StringBuilder extends AbstractStringBuilder implements Serializable, CharSequence

        StringBuilder是一个可变的字符序列。 此类提供与StringBuffer的API，相较于StringBuffer，StringBuilder不保证同步，所以不能安全使用多线程。但在非多线程的场景，性能略高于StringBuffer。读者可根据实际场景选择使用。

        基于JDK源码，笔者列出StringBuilder每个方法，希望与各位一起阅读、学习：

package java.lang;
 
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.io.StreamCorruptedException;
 
public final class StringBuilder extends AbstractStringBuilder implements Serializable, CharSequence {
    static final long serialVersionUID = 4383685877147921099L;
 
    public StringBuilder() {
        super(16);
    }
 
    public StringBuilder(int var1) {
        super(var1);
    }
 
    public StringBuilder(String var1) {
        super(var1.length() + 16);
        this.append(var1);
    }
 
    public StringBuilder(CharSequence var1) {
        this(var1.length() + 16);
        this.append(var1);
    }
 
    public StringBuilder append(Object var1) {
        return this.append(String.valueOf(var1));
    }
 
    public StringBuilder append(String var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(StringBuffer var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(CharSequence var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(CharSequence var1, int var2, int var3) {
        super.append(var1, var2, var3);
        return this;
    }
 
    public StringBuilder append(char[] var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(char[] var1, int var2, int var3) {
        super.append(var1, var2, var3);
        return this;
    }
 
    public StringBuilder append(boolean var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(char var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(int var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(long var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(float var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder append(double var1) {
        super.append(var1);
        return this;
    }
 
    public StringBuilder appendCodePoint(int var1) {
        super.appendCodePoint(var1);
        return this;
    }
 
    public StringBuilder delete(int var1, int var2) {
        super.delete(var1, var2);
        return this;
    }
 
    public StringBuilder deleteCharAt(int var1) {
        super.deleteCharAt(var1);
        return this;
    }
 
    public StringBuilder replace(int var1, int var2, String var3) {
        super.replace(var1, var2, var3);
        return this;
    }
 
    public StringBuilder insert(int var1, char[] var2, int var3, int var4) {
        super.insert(var1, var2, var3, var4);
        return this;
    }
 
    public StringBuilder insert(int var1, Object var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, String var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, char[] var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, CharSequence var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, CharSequence var2, int var3, int var4) {
        super.insert(var1, var2, var3, var4);
        return this;
    }
 
    public StringBuilder insert(int var1, boolean var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, char var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, int var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, long var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, float var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public StringBuilder insert(int var1, double var2) {
        super.insert(var1, var2);
        return this;
    }
 
    public int indexOf(String var1) {
        return super.indexOf(var1);
    }
 
    public int indexOf(String var1, int var2) {
        return super.indexOf(var1, var2);
    }
 
    public int lastIndexOf(String var1) {
        return super.lastIndexOf(var1);
    }
 
    public int lastIndexOf(String var1, int var2) {
        return super.lastIndexOf(var1, var2);
    }
 
    public StringBuilder reverse() {
        super.reverse();
        return this;
    }
 
    public String toString() {
        return new String(this.value, 0, this.count);
    }
 
    private void writeObject(ObjectOutputStream var1) throws IOException {
        var1.defaultWriteObject();
        var1.writeInt(this.count);
        var1.writeObject(this.value);
    }
 
    private void readObject(ObjectInputStream var1) throws IOException, ClassNotFoundException {
        var1.defaultReadObject();
        int var2 = var1.readInt();
        char[] var3 = (char[])((char[])var1.readObject());
        if (var2 >= 0 && var2 <= var3.length) {
            this.count = var2;
            this.value = var3;
        } else {
            throw new StreamCorruptedException("count value invalid");
        }
    }
}

        StringBuilder各方法的基本使用测试和StringBuffer基本相同，不再赘余演示，读者可以参考StringBuffer的示例，也可基于API自行测试。