public class ImageCache {
private List<byte[]> list = new ArrayList<byte[]>(); //存储所有部分缓存
private int initSize; //初始化大小，每次申请时都会申请等同于initSize大小的byte[] buf
private int size; //image cache 的实际大小
public ImageCache(int initSize){
this.initSize = initSize;
byte[] buf = new byte[initSize];
list.add(buf);
}
/**
* 返回此image对象对应的byte数组
*
*/
public byte[] getImage(){
byte[] buf = new byte[size];
int init = size;
int index = 0;
for(byte[] temp :list){
if(init < initSize){
setElement(buf, temp, 0, init, index);
break;
}else{
init = init - initSize;
setElement(buf, temp, 0, temp.length, index);
index = index + initSize;
}
}
return buf;
}
/**
*
* dest 目标数组
* src 原数组
* start 原数组开始位置
* end 原数组结束位置
* index 目标数组开始位置
*/
private void setElement(byte[] dest,byte[] src,int start ,int end,int index){
int temp = index;
for(int i = start ; i< end ; i++){
byte value = src[i];
dest[temp] = value;
temp++;
}
}
/**
* 获取实际的索引位置
*
*/
public int getIndex(){
int listSize = list.size();
int index = size - initSize * (listSize - 1 );
return index;
}
public ImageCache append(byte[] buf,int start,int end){
int length = buf.length;
if(start <0 || start >end || end >length){
throw new RuntimeException("ImageCache append param error,start:"+start+",end:"+end+",length:"+length);
}
byte[] temp = new byte[end-start];
setElement(temp, buf, start, end, 0);
return append(temp);
}
/**
* 以追加的方式向iamge对象中添加byte图像数据
* buf
*/
public ImageCache append(byte[] buf){
int length = buf.length;
int listSize = list.size();
int remain = initSize * listSize - size; //还剩余空间
byte[] bs = list.get(listSize-1);//剩余空间集合
if(remain >= length){//剩余空间多余需要的空间，直接追加
setElement(bs, buf, 0, buf.length, getIndex());
}else{//剩余空间不足，需要申请空间
setElement(bs, buf, 0, remain, getIndex());//将之前空间填满
int bufSzie = (length -remain)/initSize;// 计算还需要buf的个数
int startIndex = remain;
for(int i=0 ;i < bufSzie ;i++){
byte[] apply = new byte[initSize] ;
setElement(apply, buf, startIndex, startIndex+initSize, 0);
list.add(apply);
startIndex = startIndex + initSize;
}
byte[] apply = new byte[initSize];
setElement(apply, buf, startIndex, buf.length, 0);
list.add(apply);
}
size += length;
return this;
}
public void destroy(){
this.list = null;
this.initSize =0;
this.size = 0;
}
@Override
public String toString() {
StringBuffer buf = new StringBuffer();
buf.append("initSize:"+this.initSize+",size:"+size+",list.size:"+list.size());
buf.append(";---content--:");
printBytes(this.list, buf);
return buf.toString();
}
public int getInistSize(){
return this.initSize;
}
public List<byte[]> getList(){
return this.list;
}
public int getSize(){
return this.size;
}
public void printBytes(byte[] buf,StringBuffer sb){
for(byte temp : buf){
sb.append(temp).append(",");
}
}
private void printBytes(List<byte[]> list,StringBuffer buf){
for(byte[] temp : list){
printBytes(temp,buf);
}
}
}