void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
将字符从此字符串复制到目标字符数组。
//不能被继承
public final class StringBuffer
extends AbstractStringBuilder
implements java.io.Serializable, CharSequence{}
StringBuffer类继承AbstractStringBuilder，AbstractStringBuilder中有两个属性：
/** * The value is used for character storage. */ char[] value; /** * The count is the number of characters used. */ int count;
几个重要的方法：
1 public AbstractStringBuilder append(String str) { 2 if (str == null) str = "null"; 3 int len = str.length(); 4 ensureCapacityInternal(count + len); 5 str.getChars(0, len, value, count); 6 count += len; 7 return this; 8 }
private void ensureCapacityInternal(int minimumCapacity) { // overflow-conscious code if (minimumCapacity - value.length > 0) expandCapacity(minimumCapacity); }
void expandCapacity(int minimumCapacity) { int newCapacity = value.length * 2 + 2; if (newCapacity - minimumCapacity < 0) newCapacity = minimumCapacity; if (newCapacity < 0) { if (minimumCapacity < 0) // overflow throw new OutOfMemoryError(); newCapacity = Integer.MAX_VALUE; } value = Arrays.copyOf(value, newCapacity); }
原文：http://www.cnblogs.com/wanghui390/p/3997816.html