package net.paoding.rose.jade.statement.expression.impl;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import net.paoding.rose.jade.statement.expression.ExprResolver;
import org.apache.commons.jexl.Expression;
import org.apache.commons.jexl.ExpressionFactory;
import org.apache.commons.jexl.JexlContext;
import org.apache.commons.jexl.JexlHelper;
import org.apache.commons.lang.math.NumberUtils;
/**
* 默认使用: Apache Common Jexl 引擎实现表达式处理。
*
* @author han.liao
*/
public class ExprResolverImpl implements ExprResolver {
// 表达式的缓存
protected static final ConcurrentHashMap<String, Expression> cache = new ConcurrentHashMap<String, Expression>();
// 正则表达式
//private static final Pattern PREFIX_PATTERN = Pattern.compile( // NL
//"(\\:|\\$)([a-zA-Z0-9_]+)(\\.[a-zA-Z0-9_]+)*");
private static final Pattern PREFIX_PATTERN = Pattern.compile( // NL
"(\\:|\\$)([a-zA-Z0-9_]+)(\\.[a-zA-Z0-9_]+)*");
private static final Pattern MAP_PATTERN = Pattern.compile( // NL
"\\[([\\.a-zA-Z0-9_]+)\\]");
// 常量前缀
private static final String CONST_PREFIX = "_mapConsts";
// 参数前缀
private static final String VAR_PREFIX = "_mapVars";
// 参数表
protected final Map<String, Object> mapVars = new HashMap<String, Object>();
// 常量表
protected final Map<String, Object> mapConsts = new HashMap<String, Object>();
// Common Jexl 上下文
protected final JexlContext context = JexlHelper.createContext();
/**
* 构造表达式处理器。
*/
@SuppressWarnings("unchecked")
public ExprResolverImpl() {
Map map = context.getVars();
map.put(VAR_PREFIX, mapVars);
map.put(CONST_PREFIX, mapConsts);
}
/**
* 构造表达式处理器。
*
* @param mapVars - 初始的参数表
*/
public ExprResolverImpl(Map<String, ?> mapVars) {
this();
this.mapVars.putAll(mapVars);
}
/**
* 构造表达式处理器。
*
* @param mapVars - 初始的参数表
* @param mapConsts - 初始的常量表
*/
public ExprResolverImpl(Map<String, ?> mapVars, Map<String, ?> mapConsts) {
this();
this.mapVars.putAll(mapVars);
this.mapConsts.putAll(mapConsts);
}
/**
* 返回表达式处理器的参数表。
*
* @return 处理器的参数表
*/
public Map<String, ?> getVars() {
return mapVars;
}
/**
* 设置表达式处理器的参数表。
*
* @param map - 处理器的参数表
*/
public void setVars(Map<String, ?> map) {
mapVars.putAll(map);
}
/**
* 返回表达式处理器的常量表。
*
* @return 处理器的常量表
*/
public Map<String, ?> getConstants() {
return mapConsts;
}
/**
* 设置表达式处理器的常量表。
*
* @param map - 处理器的常量表
*/
public void setConstants(Map<String, ?> map) {
mapConsts.putAll(map);
}
@Override
public Object executeExpr(final String expression) throws Exception {
// 从缓存中获取解析的表达式
Expression expr = cache.get(expression);
if (expr == null) {
//
StringBuilder builder = new StringBuilder(expression.length() * 2);
// 将[name]替换为['name']
Matcher mapMatcher = MAP_PATTERN.matcher(expression);
int index = 0;
while (mapMatcher.find()) {
builder.append(expression.substring(index, mapMatcher.start()));
String t = mapMatcher.group(1);
if (!NumberUtils.isDigits(t)) {
builder.append("['");
builder.append(mapMatcher.group(1));
builder.append("']");
} else {
builder.append(mapMatcher.group(0));
}
index = mapMatcher.end();
}
String expression2;
if (builder.length() == 0) {
expression2 = expression;
} else {
builder.append(expression.substring(index));
expression2 = builder.toString();
builder.setLength(0);
}
index = 0;
// 匹配正则表达式, 并替换内容
Matcher matcher = PREFIX_PATTERN.matcher(expression2);
while (matcher.find()) {
builder.append(expression2.substring(index, matcher.start()));
String prefix = matcher.group(1);
String name = matcher.group(2);
if (":".equals(prefix)) {
boolean isDigits = NumberUtils.isDigits(name);
if (isDigits) {
// 按顺序访问变量
name = ':' + name;
}
if (!mapVars.containsKey(name)) {
throw new IllegalArgumentException("Variable \'" + name
+ "\' not defined in DAO method");
}
// 按名称访问变量
builder.append(VAR_PREFIX);
builder.append("['");
builder.append(name);
builder.append("']");
} else if ("$".equals(prefix)) {
if (!mapConsts.containsKey(name)) {
throw new IllegalArgumentException("Constant \'" + name
+ "\' not defined in DAO class");
}
// 拼出常量访问语句
builder.append(CONST_PREFIX);
builder.append("[\'");
builder.append(name);
builder.append("\']");
}
index = matcher.end(2);
}
builder.append(expression2.substring(index));
// 编译表达式
expr = ExpressionFactory.createExpression(builder.toString());
cache.putIfAbsent(expression2, expr);
}
// 进行表达式求值
return expr.evaluate(context);
}
@Override
public Object getVar(String variant) {
return mapVars.get(variant);
}
@Override
public void setVar(String variant, Object value) {
mapVars.put(variant, value);
}
// 进行简单测试
public static void main(String... args) throws Exception {
Map<String, Object> map = new HashMap<String, Object>();
map.put("current", new Date());
map.put("numbers", new Integer[] { 1, 2, 3, 5, 8, 13, 21, 34 });
map.put("index", 5);
map.put(":2", 2);
map.put("map", map);
ExprResolver exprResolver = new ExprResolverImpl(map, map);
System.out.println("map['index']=" + // NL
exprResolver.executeExpr(":map[index]"));
System.out.println("numbers[5]=" + // NL
exprResolver.executeExpr(":map[numbers][5]"));
System.out.println( // NL
exprResolver.executeExpr( // NL
"$numbers[:index] + :2"));
System.out.println( // NL
exprResolver.executeExpr( // NL
":current.year - ($current.month + $current.day) - :2"));
System.out.println( // NL
exprResolver.executeExpr( // NL
":current.year - ($current.month + $current.day) + $numbers[:index] + :2"));
}
public static void main2(String[] args) {
StringBuilder sb = new StringBuilder(100 * 2);
String ex = ":1.id[id.kkj][idkkj], :2[name], :3[age], :3[4]";
Matcher m = MAP_PATTERN.matcher(ex);
int index = 0;
while (m.find()) {
sb.append(ex.substring(index, m.start()));
String t = m.group(1);
if (!NumberUtils.isDigits(t)) {
sb.append("['");
sb.append(m.group(1));
sb.append("']");
} else {
sb.append(m.group(0));
}
index = m.end();
}
sb.append(ex.substring(index));
System.out.println(sb);
}
}