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安装antlr4插件
创建一个后缀是g4的文件
grammar Expr;expression :'(' expression ')' # parens| expression 'and' expression # andOp| expression 'or' expression # orOp| '@' VARNAME comparison_op NUMBER # comparison| '@' VARNAME comparison_op STRING # comparison| '@' NUMBER comparison_op NUMBER # comparison| '@' STRING comparison_op STRING # comparison| '@' VARNAME comparison_op VARNAME # comparison| '@' VARNAME contains_op VARNAME # comparison| '@' VARNAME contains_op NUMBER # comparison| '@' VARNAME contains_op STRING # comparison| '@' STRING contains_op STRING # comparison| VARNAME comparison_op NUMBER # comparison| VARNAME comparison_op STRING # comparison| NUMBER comparison_op NUMBER # comparison| STRING comparison_op STRING # comparison| VARNAME comparison_op VARNAME # comparison| VARNAME contains_op VARNAME # comparison| VARNAME contains_op NUMBER # comparison| VARNAME contains_op STRING # comparison| STRING contains_op STRING # comparison;comparison_op : '<' | '<=' | '>' | '>=' | '==' | '!=';
contains_op: 'contains' | 'notcontains';STRING : '\'' ( '\\' . | '\\\'' | ~[\\'] )* '\'';
NUMBER : '-'? [0-9]+ ('.' [0-9]+)?;
VARNAME : [a-zA-Z_][a-zA-Z_0-9]*;
WS : [ \t\r\n]+ -> skip; // 忽略空白字符
fragment Letter: [a-zA-Z];
fragment Digit: [0-9];
fragment ChineseCharacter: [\u4e00-\u9fa5];上面的文件可以直接解析如下格式的表达式：
@prices == 1 and (@val >=1 or @name<=4) and 1==1 and '2'=='3' and '1123' contains '1' and '23455' notcontains '5'
右键生成代码
引入POM
<!--动态表达式--><dependency><groupId>org.antlr</groupId><artifactId>antlr4</artifactId><version>4.10.1</version></dependency>测试表达式结构
@Testpublic void Test00(){// 构建字符流CodePointCharStream charStream = CharStreams.fromString("@prices == 1 and (@val >=1 or @name<=4) and 1==1 and '2'=='3' and '1123' contains '1' and '23455' notcontains '5'");// 从字符流分析词法， 解析为tokenExprLexer lexer = new ExprLexer(charStream);// 从token进行分析ExprParser parser = new ExprParser(new CommonTokenStream( lexer) );// 使用监听器，遍历语法树，根据语法定义，prog为语法树的根节点ParseTree prog = parser.expression();// 创建监听器CustomerExprListener listener = new CustomerExprListener();// 遍历AST并使用监听器处理ParseTreeWalker walker = new ParseTreeWalker();walker.walk(listener, prog);// 打印生成的语法树//System.out.println( prog.toStringTree(parser));}拿到表达式以后，就可以把结果处理成实际业务想要的对象了
package com.java.core.web.antlr4;import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.tree.ErrorNode;
import org.antlr.v4.runtime.tree.TerminalNode;public class CustomerExprListener extends ExprBaseListener{@Overridepublic void enterEveryRule(ParserRuleContext ctx) {//System.out.println("Entering rule: " + ctx.getText());}@Overridepublic void exitEveryRule(ParserRuleContext ctx) {//System.out.println("Exiting rule: " + ctx.getText());}@Overridepublic void visitTerminal(TerminalNode node) {System.out.println("Visiting terminal: " + node.getText());}@Overridepublic void visitErrorNode(ErrorNode node) {//System.out.println("Visiting error: " + node.getText());}
}
监听输出的内容
Visiting terminal: @
Visiting terminal: prices
Visiting terminal: ==
Visiting terminal: 1
Visiting terminal: and
Visiting terminal: (
Visiting terminal: @
Visiting terminal: val
Visiting terminal: >=
Visiting terminal: 1
Visiting terminal: or
Visiting terminal: @
Visiting terminal: name
Visiting terminal: <=
Visiting terminal: 4
Visiting terminal: )
Visiting terminal: and
Visiting terminal: 1
Visiting terminal: ==
Visiting terminal: 1
Visiting terminal: and
Visiting terminal: '2'
Visiting terminal: ==
Visiting terminal: '3'
Visiting terminal: and
Visiting terminal: '1123'
Visiting terminal: contains
Visiting terminal: '1'
Visiting terminal: and
Visiting terminal: '23455'
Visiting terminal: notcontains
Visiting terminal: '5'可以把监控的类提取出来
/*** 遍历语法树节点* @param tree*/public static RuleTest traverseTree(ParseTree tree, String name, RuleTest ruleTest) {//自定义变量// public String type; //类型 1-属性 2-值 （由比较操作符决定）// public String group; //组 0-不用添加组 1-需要添加组 （由连续小括号的数量决定，如果两个符号连续都是小括号，那么系统会认为是一个组）// public String bracket;//括号 判断是否是组 （小括号的数量记录）// public String isObject;//是否new object （条件对象 0-不创建 1-创建 由逻辑运算符决定 如 and/or）if (tree instanceof TerminalNode) {TerminalNode terminalNode = (TerminalNode) tree;//得到树节点String text = terminalNode.getText();//获取条件组List<Condition> list = ruleTest.getConditionList();//判断节点类型 （比较操作符/逻辑运算符号/小括号/中括号/@符）int res = CheckSymbolOptions.getNameOrValue(text);if (res == 1){ //比较操作符ruleTest.setType("2");ruleTest.setEndBracket("0");if (ruleTest.getGroup() == null || ruleTest.getGroup().equals("0")){if (list.size()>0){Condition condition = list.get(list.size()-1);String symbolOptions = SymbolOptions.getNameOrValue(text);condition.setCompareOperation(symbolOptions);//比较操作（操作符）}}else{Condition cond = list.get(list.size()-1);List<Condition> conditionList = cond.getConditionList();if (conditionList.size()>0){Condition condition = conditionList.get(conditionList.size()-1);String symbolOptions = SymbolOptions.getNameOrValue(text);condition.setCompareOperation(symbolOptions);//比较操作（操作符）}}}else if (res ==2){ //逻辑运算符if (ruleTest.getGroup() == null || ruleTest.getGroup().equals("0")){//添加条件对象Condition condition = addCondition(name,"symbol",text);list.add(condition);ruleTest.setIsObject("1");//需要添加条件对象 0-不添加 1-添加}else{Condition cond = list.get(list.size()-1);List<Condition> conditionList = cond.getConditionList();//添加条件对象Condition condition = addCondition(name,"symbol",text);conditionList.add(condition);ruleTest.setIsObject("1");//需要添加条件对象 0-不添加 1-添加}}else if (res==3){ //括号标识符if (text.equals("(")){ruleTest.setType("1");if (ruleTest.getBracket()==null || ruleTest.getBracket().equals("0")){ruleTest.setBracket("1");}else{int va = Integer.valueOf(ruleTest.getBracket())+1;ruleTest.setBracket(String.valueOf(va));if (va==2){if (list== null){list = new ArrayList<>();}ruleTest.setGroup("1");
// if (list.size()==0){
// Condition condition = addCondition(name,"group",null);
// int endva = Integer.valueOf(ruleTest.getSubscript())+1;
// ruleTest.setSubscript(String.valueOf(endva));//记录下标
// condition.setTierIndex(String.valueOf(endva));
// list.add(condition);
// ruleTest.setConditionList(list);
// }//创建对象Condition condition = addCondition(name,"group",null);condition.setDescribe(null);int endva = Integer.valueOf(ruleTest.getSubscript())+1;ruleTest.setSubscript(String.valueOf(endva));//记录下标condition.setTierIndex(String.valueOf(endva));list.add(condition);ruleTest.setConditionList(list);ruleTest.setIsObject("0");//添加对象后回复初始状态}ruleTest.setBracket("0");}if (ruleTest.getId()==null){//设置rule属性ruleTest.setId(generateId("rule"));//id需要自动生成 rule_xxxxxxxxxx（10位数）ruleTest.setName(name);ruleTest.setSubscript("1");//记录索引ruleTest.setTierIndex("1");//层级索引 需要确定来源}}if (text.equals(")")){if (ruleTest.getEndBracket()==null || ruleTest.getEndBracket().equals("0")){ruleTest.setEndBracket("1");}else{int endva = Integer.valueOf(ruleTest.getEndBracket())+1;ruleTest.setEndBracket(String.valueOf(endva));}if (ruleTest.getEndBracket().equals("2")){ruleTest.setGroup("0");}}}else if (res ==4){ //@ 参数标识ruleTest.setType("1");}else {//初始化对象与集合if (list== null || list.size()==0){list = new ArrayList<>();Condition condition = addCondition(name,"single",null);list.add(condition);ruleTest.setConditionList(list);}if (ruleTest.getGroup() == null || ruleTest.getGroup().equals("0")){if (ruleTest.getIsObject()!=null){if (ruleTest.getIsObject().equals("1")){//创建对象
// Condition condition = new Condition();Condition condition = addCondition(name,"single",null);list.add(condition);ruleTest.setIsObject("0");//添加对象后回复初始状态}}}else{if (ruleTest.getIsObject()!=null){if (ruleTest.getIsObject().equals("1")) {Condition cond = list.get(list.size()-1);List<Condition> conditionList = cond.getConditionList();//创建对象Condition addCondition = addCondition(name,"single",null);conditionList.add(addCondition);ruleTest.setIsObject("0");//添加对象后回复初始状态}}}if (list.size()>0){if (ruleTest.getGroup()== null || ruleTest.getGroup().equals("0") ){//获取属性详情，判断属性是否存在，如果存在拿到属性名称、类型等信息String type = DataType.getDataType("5000"); //此处需要替换Condition condition = list.get(list.size()-1);if (condition.getLeftOperatorExpression()==null || condition.getRightOperatorExpression()==null ){if (ruleTest.getType().equals("1")){//创建左边运算符表达式LeftOperatorExpression left = addLeftOperatorExpression(type,text);condition.setLeftOperatorExpression(left);ruleTest.setType("0");}if (ruleTest.getType().equals("2")){//创建右边运算符表达式RightOperatorExpression right = addRightOperatorExpression(type,text);condition.setRightOperatorExpression(right);ruleTest.setType("0");ruleTest.setBracket("0");}}}else{if (ruleTest.getGroup().equals("1")){String type = DataType.getDataType("5000"); //此处需要替换Condition cond = list.get(list.size()-1);
// Rule rule = cond.getRule();List<Condition> conditionList = cond.getConditionList();//初始化对象与集合if (conditionList== null || conditionList.size()==0){conditionList = new ArrayList<>();Condition condition = addCondition(name,"single",null);if (condition.getLeftOperatorExpression() == null || condition.getRightOperatorExpression() == null) {if (ruleTest.getType().equals("1")) {//创建左边运算符表达式LeftOperatorExpression left = addLeftOperatorExpression(type, text);condition.setLeftOperatorExpression(left);ruleTest.setType("0");}if (ruleTest.getType().equals("2")) {//创建右边运算符表达式RightOperatorExpression right = addRightOperatorExpression(type, text);condition.setRightOperatorExpression(right);ruleTest.setType("0");ruleTest.setBracket("0");}}conditionList.add(condition);cond.setConditionList(conditionList);}else{Condition condition = conditionList.get(conditionList.size()-1);if (condition.getLeftOperatorExpression() == null || condition.getRightOperatorExpression() == null) {if (ruleTest.getType().equals("1")) {//创建左边运算符表达式LeftOperatorExpression left = addLeftOperatorExpression(type, text);condition.setLeftOperatorExpression(left);ruleTest.setType("0");}if (ruleTest.getType().equals("2")) {//创建右边运算符表达式RightOperatorExpression right = addRightOperatorExpression(type, text);condition.setRightOperatorExpression(right);ruleTest.setType("0");ruleTest.setBracket("0");}}}}}}}}//递归 循环遍历for (int i = 0; i < tree.getChildCount(); i++) {traverseTree(tree.getChild(i),name,ruleTest);}return ruleTest;}这篇关于JAVA动态表达式：Antlr4 G4 模板 + 读取字符串表达式结构树的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
