Solrj JavaBinCodec分析
solr请求回来的数据为字节流，solrj通过JavaBinCodec对其进行解析。
一、JavaBinCodec的主要标识tag
各tag的定义：
public static final byte
NULL = 0,
BOOL_TRUE = 1,
BOOL_FALSE = 2,
BYTE = 3,
SHORT = 4,
DOUBLE = 5,
INT = 6,
LONG = 7,
FLOAT = 8,
DATE = 9,
MAP = 10,
SOLRDOC = 11, //SolrDocument对象,会先读取SortedMap，然后setField到SolrDocument中
SOLRDOCLST = 12, //SolrDocumentList对象，会先读一个长度为3的list即arr，并设置numFound,start,maxScore3个值，然后再读一个list,即doc的list
BYTEARR = 13,
ITERATOR = 14,
/**
* this is a special tag signals an end. No value is associated with it
*/
END = 15,
SOLRINPUTDOC = 16,
SOLRINPUTDOC_CHILDS = 17,
ENUM_FIELD_VALUE = 18,
// types that combine tag + length (or other info) in a single byte//这些tag除了表示tag外还包括了其子元素的个数或其他信息
TAG_AND_LEN = (byte) (1 << 5),
STR = (byte) (1 << 5), //表示字符串以及长度，tag范围32～63，&0x1f后得到的就是字符串长度
SINT = (byte) (2 << 5), //表示small int以及长度，tag范围32～95,&0x1f后得到的就是sint的长度
SLONG = (byte) (3 << 5), //表示small long以及长度，tag范围96～111, &0x0f后得到的就是slong的长度
ARR = (byte) (4 << 5), //表示数组以及数组元素个数, tag范围-113~-128, &0x0f后得到的就是数组元素个数
ORDERED_MAP = (byte) (5 << 5), // SimpleOrderedMap (a NamedList subclass, and more common)。Key-->Value,Key是先读EXTERN_STRING，再读Str即真正的key值。范围-65~-96。
NAMED_LST = (byte) (6 << 5), // NamedList，范围-33~-64
EXTERN_STRING = (byte) (7 << 5);//map中的keyvalue的key时会用此tag。 范围-32二、JavaBinCodec主要方法
1、最主要的方法：readVal()
public Object readVal(DataInputInputStream dis) throws IOException {
tagByte = dis.readByte();
// if ((tagByte & 0xe0) == 0) {
// if top 3 bits are clear, this is a normal tag
// OK, try type + size in single byte
switch (tagByte >>> 5) {
case STR >>> 5:
return readStr(dis);
case SINT >>> 5:
return readSmallInt(dis);
case SLONG >>> 5:
return readSmallLong(dis);
case ARR >>> 5:
return readArray(dis);
case ORDERED_MAP >>> 5:
return readOrderedMap(dis);
case NAMED_LST >>> 5:
return readNamedList(dis);
case EXTERN_STRING >>> 5:
return readExternString(dis);
}
switch (tagByte) {
case NULL:
return null;
case DATE:
return new Date(dis.readLong());
case INT:
return dis.readInt();
case BOOL_TRUE:
return Boolean.TRUE;
case BOOL_FALSE:
return Boolean.FALSE;
case FLOAT:
return dis.readFloat();
case DOUBLE:
return dis.readDouble();
case LONG:
return dis.readLong();
case BYTE:
return dis.readByte();
case SHORT:
return dis.readShort();
case MAP:
return readMap(dis);
case SOLRDOC:
return readSolrDocument(dis);
case SOLRDOCLST:
return readSolrDocumentList(dis);
case BYTEARR:
return readByteArray(dis);
case ITERATOR:
return readIterator(dis);
case END:
return END_OBJ;
case SOLRINPUTDOC:
return readSolrInputDocument(dis);
case ENUM_FIELD_VALUE:
return readEnumFieldValue(dis);
}
throw new RuntimeException("Unknown type " + tagByte);
}2、readSolrDocumentList：读SolrDocumentList
//先得到numFound,start,maxScore三个属性的值，存于List中，设置到solrdocumentlist对象中，再找其包含的doclist
public SolrDocumentList readSolrDocumentList(DataInputInputStream dis) throws IOException {
SolrDocumentList solrDocs = new SolrDocumentList();
List list = (List) readVal(dis);
solrDocs.setNumFound((Long) list.get(0));
solrDocs.setStart((Long) list.get(1));
solrDocs.setMaxScore((Float) list.get(2));
@SuppressWarnings("unchecked")
List<SolrDocument> l = (List<SolrDocument>) readVal(dis);
solrDocs.addAll(l);
return solrDocs;
}3、readSolrDocument：读一个doc
//先获得NameList，再放到doc中
public SolrDocument readSolrDocument(DataInputInputStream dis) throws IOException {
NamedList nl = (NamedList) readVal(dis);//结果其实是OrderedMap，会被转成NamedList
SolrDocument doc = new SolrDocument();
for (int i = 0; i < nl.size(); i++) {
String name = nl.getName(i);
Object val = nl.getVal(i);
doc.setField(name, val);
}
return doc;
}4、readOrderedMap:读map
//先key后value，key时有EXTERN_STRING的Tag，再是Str_tag
public SimpleOrderedMap<Object> readOrderedMap(DataInputInputStream dis) throws IOException {
int sz = readSize(dis);
SimpleOrderedMap<Object> nl = new SimpleOrderedMap<Object>();
for (int i = 0; i < sz; i++) {
String name = (String) readVal(dis);
Object val = readVal(dis);//读完key后会读value
nl.add(name, val);
}
return nl;
}5、readArray:读数组list
//
public List<Object> readArray(DataInputInputStream dis) throws IOException {
int sz = readSize(dis);
ArrayList<Object> l = new ArrayList<Object>(sz);
for (int i = 0; i < sz; i++) {
l.add(readVal(dis));
}
return l;
}6、readSize：将tag &0x1f获得大小
public int readSize(DataInputInputStream in) throws IOException {
int sz = tagByte & 0x1f; //即如果tagByte<31 (0x1f是31), 则tag还表示个数。
if (sz == 0x1f) sz += readVInt(in); //如果太大，则下一个内容就是大小
return sz;
}7、readSmallInt: &0x0f得到长度
public int readSmallInt(DataInputInputStream dis) throws IOException {
int v = tagByte & 0x0F;
if ((tagByte & 0x10) != 0)
v = (readVInt(dis) << 4) | v;
return v;
}8、readExternString
//
public String readExternString(DataInputInputStream fis) throws IOException {
int idx = readSize(fis);
if (idx != 0) {// idx != 0 is the index of the extern string 字符串索引
return stringsList.get(idx - 1);
} else {// idx == 0 means it has a string value 即后面是字符串
String s = (String) readVal(fis);
if (stringsList == null) stringsList = new ArrayList<String>();
stringsList.add(s);
return s;
}
}三、举例
返回的byte:
2, -94, -32, 46, 114, 101, 115, 112, 111, 110, 115, 101, 72, 101, 97, 100, 101, 114, -93, -32, 38, 115, 116, 97, 116, 117, 115, 6, 0, 0, 0, 0, -32, 37, 81, 84, 105, 109, 101, 6, 0, 0, 0, 0, -32, 38, 112, 97, 114, 97, 109, 115, -93, -32, 33, 113, 36, 105, 100, 58, 49, -32, 34, 119, 116, 39, 106, 97, 118, 97, 98, 105, 110, -32, 39, 118, 101, 114, 115, 105, 111, 110, 33, 50, -32, 40, 114, 101, 115, 112, 111, 110, 115, 101, 12, -125, 97, 96, 0, -127, 11, -93, -32, 34, 105, 100, 33, 49, -32, 36, 110, 97, 109, 101, 33, 49, -32, 41, 95, 118, 101, 114, 115, 105, 111, 110, 95, 7, 20, 43, 47, -61, -44, 64, 0, 0
解析完的结果：
{responseHeader={status=0,QTime=0,params={q=id:1,wt=javabin,version=2}},response={numFound=1,start=0,docs=[SolrDocument{id=1, name=1, _version_=1453307822883209216}]}}解析过程分析：
版本, ORDERED_MAP Tag(read size: -94&0x1f结果为2，即有两个keyvalue), //第一个keyvalue EXTERN_STRING Tag, 字符串长度(46&0x1f=14), responseHeader, ORDERED_MAP Tag(read size: -93&0x1f结果为3), EXTERN_STRING Tag, Str tag(32是str的tag)字符串长度(38&0x1f=6), status, 下个值是int型(6表示int)(ordermap的key读取完后就会读value), 0(4byte), EXTERN_STRING Tag, 字符串长度(37&0x1f=5), QTime, 下个值是int型(6表示int)(ordermap的key读取完后就会读value), 0(4byte), EXTERN_STRING Tag, 字符串长度(38&0x1f=6), params, ORDERED_MAP Tag(read size: -94&0x1f结果为3), EXTERN_STRING Tag, 字符串长度(33&0x1f=1), q, STR TAG(下个值是string)(36&0x1f=4，即有4个字符), id:1, EXTERN_STRING Tag, 字符串长度(34&0x1f=2), wt, STR TAG(下个值是string)(39&0x1f=7，即有7个字符), javabin, EXTERN_STRING Tag, 字符串长度(39&0x1f=7), version, STR TAG(下个值是string)(33&0x1f=1，即有1个字符), 2, //第二个keyvalue EXTERN_STRING Tag, 字符串长度(40&0x1f=8), response, SOLRDOCLST TAG(12是doclist，即SolrDocumentList对象，有属性numFound,start,maxScore，以及自身是ArrayList<SolrDocument>), ARRAY TAG(-128是arr tag)(-125&0x1f=3, 即有3个属性)(后面的三个属性分别是numFound,start,maxScore,详见readSolrDocumentList), SLONG Tag(96是smalllong tag)(97&0x0f=1)结果是1, SLONG Tag(96&0x0f=0)结果是0, NULL Tag(0表示null), ARRAY Tag(-127&0x1f=1,即有一个元素)(该产生的list会被前面的solrdocumentlist.addAll(list)), SOLRDOC Tag(11是solrdoc tag), ORDERED_MAP Tag(read size: -93&0x1f结果为3), EXTERN_STRING Tag, Str Tag字符串长度(34&0x1f=2), id, Str Tag字符串长度(33&0x1f=1), 1, EXTERN_STRING Tag, Str Tag字符串长度(36&0x1f=4), name, Str Tag字符串长度(33&0x1f=1), 1, EXTERN_STRING Tag, Str Tag字符串长度(41&0x1f=9), _version_, Long Tag(7是Long Tag), 1453307822883209216
注：
(1453307822883209216=1010000101011001011111100001111010100010000000000000000000000)(20=00010100,43=00101011,47=00101111,-61=11000011,-44=11010100,64=01000000,0=00000000,0=00000000)