{"id":196,"date":"2007-08-03T13:54:38","date_gmt":"2007-08-03T05:54:38","guid":{"rendered":"https:\/\/lifeparty.idv.tw\/blog\/archives\/196"},"modified":"2007-08-03T17:49:59","modified_gmt":"2007-08-03T09:49:59","slug":"%e6%b0%b8%e7%ba%8c%e7%89%a9%e4%bb%b6%e6%9f%a5%e8%a9%a2%e4%b9%8b%e8%a8%ad%e8%a8%88%ef%bc%88%e5%85%b6%e4%ba%8c%ef%bc%89","status":"publish","type":"post","link":"https:\/\/lifeparty.idv.tw\/blog\/archives\/196","title":{"rendered":"\u6c38\u7e8c\u7269\u4ef6\u67e5\u8a62\u4e4b\u8a2d\u8a08\uff08\u5176\u4e8c\uff09"},"content":{"rendered":"

\u524d\u6587<\/a>\u63d0\u5230\u5728\u67e5\u8a62\u6c38\u7e8c<\/a>\u7269\u4ef6\u7684\u5f8c\u7aef\u5be6\u4f5c<\/a>\u4e0a\uff0c\u5728\u8655\u7406 where \u689d\u4ef6\u5f0f\u7684\u90e8\u5206\uff0c\u5c0d\u65bc\u7269\u4ef6\u67e5\u8a62\u7684\u6a39\u72c0\u7d50\u69cb<\/a>\u689d\u4ef6\u8868\u793a\u5f0f\u800c\u8a00\uff0c\u53ef\u4ee5\u904b\u7528 GOF<\/a> \u7684 interpreter pattern<\/a> \u7684\u89c0\u5ff5\uff0c\u85c9\u7531\u5c0b\u8a2a\u8a9e\u6cd5\u6a39\u7684\u904e\u7a0b\u4e2d\u4f86\u4e88\u4ee5\u89e3\u6790\u540c\u6642\u52a0\u4ee5\u8655\u7406\u3002<\/p>\n

\u4f46\u5728\u5be6\u4f5c\u7684\u8003\u91cf\u4e0a\uff0c\u76f8\u540c\u7684\u689d\u4ef6\u8868\u793a\u5f0f\u5728\u89e3\u6790\u8655\u7406\u4e0a\u537b\u5fc5\u9808\u96a8\u8457\u63a1\u7528\u7684\u6c38\u7e8c\u6846\u67b6<\/a>\u800c\u6709\u6240\u8b8a\u5316\u3002\u56e0\u6b64\uff0c\u89e3\u6790\u8655\u7406\u7684\u5be6\u4f5c\u4e26\u4e0d\u80fd\u653e\u5728 QueryExpression \u4e2d\uff0c\u800c\u662f\u5fc5\u9808\u5c07\u89e3\u6790\u8655\u7406\u7684\u6982\u5ff5\u5c01\u88dd\u70ba\u5c0b\u8a2a\u5668\u7684\u754c\u9762\uff0c\u8b93 QueryExpression \u53ef\u63a5\u53d7\u4e0d\u540c\u5c0b\u8a2a\u5668\uff0c\u4ee5\u5bb9\u7d0d\u53ef\u91dd\u5c0d\u63a1\u7528\u4e0d\u540c\u6c38\u7e8c\u6846\u67b6\u800c\u6709\u4e0d\u540c\u89e3\u6790\u8655\u7406\u7684\u529f\u80fd\u3002<\/p>\n

\u6b64\u7a2e\u505a\u6cd5\u5176\u5be6\u5c31\u662f\u5229\u7528 GOF \u7684 visitor pattern<\/a> \u4f86\u589e\u52a0\u7cfb\u7d71\u8a2d\u8a08\u7684\u5f48\u6027\uff0c\u4f46\u9650\u65bc\u7bc7\u5e45\uff0c\u524d\u6587\u4e26\u672a\u4ea4\u5f85\u8981\u5982\u4f55\u505a\uff0c\u672c\u6587\u5c31\u662f\u8981\u63a5\u7e8c\u9019\u500b\u554f\u984c\u4f86\u505a\u5f8c\u7e8c\u63a2\u8a0e\u3002\u9996\u5148\uff0c\u6211\u5011\u5b9a\u7fa9\u7528\u4f86\u89e3\u6790\u8655\u7406\u6a39\u72c0\u7d50\u69cb\u4e4b\u689d\u4ef6\u8868\u793a\u5f0f\u7684\u5c0b\u8a2a\u5668\u754c\u9762\uff0c\u5373 QueryExpressionVistior\uff0c\u5b83\u77e5\u9053\u5982\u4f55\u5c0b\u8a2a\u689d\u4ef6\u8868\u793a\u5f0f\u4e2d\u7684\u5404\u7a2e\u8cc7\u6599\u578b\u614b\u3002\u7136\u5f8c\u8b93 QueryExpression \u53ef\u4ee5\u63a5\u53d7\u4e0d\u540c\u7684\u5c0b\u8a2a\u5668\u4f86\u89e3\u6790\u8655\u7406\u689d\u4ef6\u8868\u793a\u5f0f\uff1a
\n
\n
\npublic interface QueryExpression {
\n public void visitPropertyExpression(
\n PropertyExpression expression,
\n ExpressionContext context);
\n public void visitScalarExpression(
\n ScalarExpression expression,
\n ExpressionContext context);
\n public void visitScalarComparisonExpression(
\n ScalarComparisonExpression expression,
\n ExpressionContext context);
\n public void visitRelationExpression(
\n RelationExpression expression,
\n ExpressionContext context);
\n …
\n}<\/p>\n

public interface QueryExpression {
\n public void accept(
\n QueryExpressionVisitor visitor);
\n}<\/p>\n

public interface ScalarExpression
\n extends QueryExpression {
\n public Object getValue(
\n ExpressionContext context);
\n}
\n…
\n<\/coolcode>
\n\u9019\u6bb5\u7a0b\u5f0f\uff0c\u540c\u4eba\u7528 ScalarExpression \u4f86\u7576\u6210 ParameterExpression\u3001ConstantExpression \u7684\u4e00\u822c\u5316<\/a>\u62bd\u8c61\u6982\u5ff5<\/a>\uff0c\u5728\u89e3\u6790\u8655\u7406\u8a9e\u6cd5\u6a39\u7684\u904e\u7a0b\u7576\u4e2d\uff0c\u53ef\u900f\u904e getValue method<\/a>\uff0c\u4f9d\u64da\u50b3\u5165\u7684\u8a9e\u5883\uff08\u8a18\u9304\u8868\u793a\u5f0f\u4e2d\u53c3\u6578\u4e4b\u503c\uff09 ExpressionContext \u4f86\u53d6\u5f97\u8b8a\u6578\u7684\u5be6\u969b\u503c\uff0c\u4ee5\u4f9b\u4ee3\u5165\u689d\u4ef6\u5f0f\u4e2d\u3002<\/p>\n

\u5728\u6b64\u53ea\u7c21\u55ae\u5c55\u793a\u5728\u524d\u6587\u7684\u7a0b\u5f0f\u7247\u6bb5\u4e2d\u66fe\u5217\u51fa\u689d\u4ef6\u8868\u793a\u5f0f\u3002\u5728\u5be6\u52d9\u4e0a\uff0c\u7a0b\u5f0f\u958b\u767c\u53ef\u80fd\u9700\u8981\u66f4\u591a\u7a2e\u985e\u7684 QueryExpression\uff0c\u4f8b\u5982\u5728\u6bd4\u8f03\u5f0f\u4e2d\uff0c\u4ea6\u5e38\u898b in\u3001between\u3001not\u3001is (not) null \u7b49\u904b\u7b97\u5b50\uff0c\u6216\u5728\u6bd4\u8f03\u8868\u793a\u5f0f\u4e2d\u6709\u95dc\u6c38\u7e8c\u7269\u4ef6\u5c6c\u6027\u7684\u76f8\u4e92\u6bd4\u8f03\u7b49\uff0c\u9650\u65bc\u7bc7\u5e45\uff0c\u672c\u6587\u7121\u6cd5\u5168\u90e8\u63d0\u5230\u3002\u4f46\u4f9d\u672c\u7bc7\u6240\u63d0\u5230\u7684\u8a2d\u8a08\u89c0\u9ede\uff0c\u5176\u5be6\u5f88\u8f15\u6613\u5730\uff0c\u53ef\u4ee5\u81ea\u884c\u8209\u4e00\u53cd\u4e09\u3002\u65bc\u662f\uff0c\u5728\u524d\u6587\u7684 HqlQueryBuilder \u7684 buildWhere \u5c31\u6703\u50cf\u9019\u6bb5\u7a0b\u5f0f\u6240\u793a\uff1a
\n
\n…
\n public void buildWhere(
\n QueryExpression expression,
\n ExpressionContext context) {
\n HqlQueryExpressionVisitor visitor =
\n new HqlQueryExpressionVisitor(
\n context);<\/p>\n

expression.accept(visitor);
\n whereClause = visitor.getWhereClause();
\n }
\n…
\npublic class HqlQueryExpressionVisitor
\n implements QueryExpressionVisitor {
\n …
\n public void visitPropertyExpression(
\n PropertyExpression expression,
\n ExpressionContext context) {
\n hqlText = expression.getName();
\n }<\/p>\n

public void visitScalarExpression(
\n ScalarExpression expression,
\n ExpressionContext context) {
\n hqlText = expression.getValue(context);
\n }<\/p>\n

public void visitScalarComparisonExpression(
\n ScalarComparisonExpression expression,
\n ExpressionContext context) {
\n HqlQueryExpressionVisitor leftVisitor =
\n new HqlQueryExpressionVisitor(
\n context);
\n HqlQueryExpressionVisitor rightVisitor =
\n new HqlQueryExpressionVisitor(
\n context);<\/p>\n

expression.getProperty()
\n .accept(leftVisitor);
\n expression.getScalar()
\n .accept(rightVisitor);
\n hqlText = leftVisitor.getHqlText() +
\n expression.operatorText() +
\n rightVisitor.getHqlText();
\n }<\/p>\n

public void visitRelationExpression(
\n RelationExpression expression) {
\n int count = expression.getCount();
\n QueryExpression [] expressions =
\n expression.getExpressions;<\/p>\n

if (count > 1) {
\n List hqlList = new ArrayList();
\n for (int i = 0; i < count; i++) {\n HqlQueryExpressionVisitor v = \n new HqlQueryExpressionVisitor(\n context);\n\n expressions[i].accept(v);\n String itemHqlText = \n v.getHqlText();\n hqlList.add(itemHqlText);\n }\n StringBuffer sb = new StringBuffer();\n\n for (i = 0; i < hqlList.size(); i++) {\n if (i > 0) {
\n sb.append(SPACE);
\n sb.append(
\n expression.getOperator());
\n }
\n sb.append(LEFT_PARENTHESIS);
\n sb.append(hqlList.get(i));
\n sb.append(RIGHT_PARENTHESIS);
\n }
\n hqlText = sb.toString();
\n }
\n else if (count > 0) {
\n expressions[0].accept(this);
\n }
\n }
\n …
\n}
\n…
\n<\/coolcode>
\n\u5f9e\u9019\u4e00\u6bb5\u7a0b\u5f0f\uff0c\u4e0d\u96e3\u7406\u89e3\u5c0b\u8a2a\u5668\u89e3\u6790\u8655\u7406\u689d\u4ef6\u8868\u793a\u5f0f\u7684\u904e\u7a0b\uff0c\u9996\u5148\u7531\u89e3\u6790\u8005\u5efa\u7acb\u8a9e\u6cd5\u89e3\u6790\u5c0b\u8a2a\u5668\uff0c\u4e26\u8a2d\u5b9a\u597d\u8981\u689d\u4ef6\u8868\u793a\u5f0f\u7684\u8a9e\u5883\uff0c\u70ba\u4e86\u7a0b\u5f0f\u7684\u7c21\u6f54\u6027\u8003\u91cf\uff0c\u6211\u5011\u5c07HQL\u7684\u8a9e\u6cd5\u89e3\u6790\u5c0b\u8a2a\u5668\u7684\u5efa\u69cb\u5b50\u52a0\u4e0a\u8a9e\u5883 ExpressionContext \u7576\u53c3\u6578\u3002\u5c0b\u8a2a\u5668\u5728\u89e3\u6790\u8655\u7406\u5b8c\u6210\u5f8c\uff0c\u6703\u5c07\u89e3\u6790\u8655\u7406\u7d50\u679c\u5b58\u5728\u5c0b\u8a2a\u5668\u5167\u90e8\u7684\u7d50\u69cb\uff0c\u53ef\u4f9b\u89e3\u6790\u8005\u53d6\u56de\uff0c\u9019\u7a2e\u904b\u4f5c\u65b9\u5f0f\u5176\u5be6\u548c builder pattern \u5982\u51fa\u4e00\u8f4d\u3002<\/p>\n

\u800c\u5728 visitXXX \u7684\u5be6\u4f5c\u65b9\u9762\uff0c\u5982\u679c QueryExpression \u6709\u5b50\u7bc0\u9ede\u6642\uff0c\u5247\u5148\u5efa\u7acb\u65b0\u7684\u8a9e\u6cd5\u89e3\u6790\u5c0b\u8a2a\u5668\u4f86\u89e3\u6790\u8655\u7406\u5b50\u7bc0\u9ede\uff0c\u7136\u5f8c\u518d\u6574\u5408\u5b8c\u6574\u7684 HQL \u8868\u793a\u5f0f\uff0c\u9019\u6a23\u5c31\u53ef\u8f15\u6613\u5730\u8655\u7406\u8907\u5408\u689d\u4ef6\u5f0f\u7684\u8a9e\u6cd5\uff0c\u5982\u4e0a\u6bb5\u7a0b\u5f0f\u4e2d\u7684 RelationExpression \u53ca ComparisonExpression\uff0c\u5176\u904b\u4f5c\u539f\u7406\u4e26\u4e0d\u8907\u96dc\u4e14\u5145\u6eff\u5f48\u6027\u3002<\/p>\n

\u4ee5\u4e0a\u4fbf\u662f\u540c\u4eba\u5728\u6c38\u7e8c\u7269\u4ef6\u67e5\u8a62\u7684\u4e3b\u8981\u8a2d\u8a08\u60f3\u6cd5\uff0c\u540c\u6642\u4e5f\u6982\u8ff0\u4e86\u5176\u5be6\u73fe\u7684\u904e\u7a0b\uff0c\u9019\u904e\u7a0b\u5176\u5be6\u4e0d\u96e3\u9ad4\u6703\u5230\u6709\u95dc builder pattern \u53ca visitor pattern \u7684\u4e0d\u540c\u904b\u7528\u3002builder pattern \u8207 visitor pattern \u53ef\u7528\u4f86\u89e3\u9664\u5be6\u4f5c\u8207\u8cc7\u6599\u7d50\u69cb\u7684\u8026\u5408\u5ea6\u3002\u9019\u5169\u8005\u90fd\u53ef\u4ee5\u4f9d\u64da\u76f8\u540c\u7684\u8cc7\u6599\u7d50\u69cb\u4f86\u5c0d\u8cc7\u6599\u505a\u4e0d\u540c\u7684\u8655\u7406\uff0c\u5b83\u5011\u90fd\u6703\u4fdd\u7559\u8655\u7406\u904e\u7a0b\u7684\u72c0\u614b\uff0c\u7b49\u5230\u8cc7\u6599\u8655\u7406\u5b8c\u6210\u5f8c\u518d\u7531\u547c\u53eb\u8005\u81ea\u884c\u53d6\u56de\u3002<\/p>\n

\u7136\u800c\uff0c\u5169\u8005\u8f03\u5927\u7684\u4e0d\u540c\u7684\u662f builder pattern \u9069\u7528\u8f03\u55ae\u7d14\u7684\u8cc7\u6599\u7d50\u69cb\uff0c\u904b\u4f5c\u904e\u7a0b\u591a\u4ee5\u53cd\u8986\u65b9\u5f0f\u8655\u7406\u8cc7\u6599\u3002\u6240\u4ee5\uff0c\u53ef\u4ee5\u628a\u901a\u7528\u6027\u7684\u63a7\u5236\u6d41\u7a0b\u62bd\u53d6\u6210 Director\uff0c\u628a\u5dee\u7570\u6027\u7684\u8cc7\u6599\u8655\u7406\u5c01\u88dd\u6210 Builder \u754c\u9762\uff0c\u4ee5\u5be6\u73fe\u4e0d\u540c\u7684 Builder \u5be6\u4f5c\uff0c\u800c\u9054\u5230\u64f4\u5145\u529f\u80fd\u7684\u76ee\u7684\u3002<\/p>\n

visitor pattern \u5247\u662f\u9069\u7528\u65bc\u8f03\u8907\u96dc\u7684\u6a39\u72c0\u7d50\u69cb\uff0c\u904b\u4f5c\u904e\u7a0b\u4e2d\uff0c\u5927\u90e8\u4efd\u662f\u7528\u968e\u5c64\u65b9\u5f0f\u8655\u7406\u8cc7\u6599\u3002\u56e0\u6b64\uff0c\u5b83\u4e26\u4e0d\u9700\u8981 Director \u4f86\u4e3b\u5c0e\u8655\u7406\u8cc7\u6599\u7684\u6d41\u7a0b\uff0c\u800c\u662f\u5c07\u5177\u5dee\u7570\u6027\u7684\u8cc7\u6599\u8655\u7406\u5c01\u88dd\u6210 Visitor \u754c\u9762\uff0c\u8b93\u5b83\u540c\u6642\u8ca0\u6709\u5c0b\u8a2a\u53ca\u8655\u7406\u8cc7\u6599\u7684\u4efb\u52d9\uff0c\u800c\u5be6\u4f5c\u8005\u4e5f\u53ef\u85c9\u7531\u5be6\u73fe\u4e0d\u540c\u8655\u7406\u7684 Visitor \u5be6\u4f5c\uff0c\u4f86\u9054\u5230\u64f4\u5145\u529f\u80fd\u7684\u76ee\u7684\u3002<\/p>\n

Design pattern<\/a> \u7684\u904b\u7528\u5e38\u5e38\u662f\u5bb9\u6613\u8b93\u958b\u767c\u8005\u7522\u751f\u7591\u60d1\u53ca\u6df7\u6dc6\u7684\u5730\u65b9\u3002\u96d6\u7136 design pattern \u53ef\u4ee5\u8b93\u6211\u5011\u5728\u9762\u5c0d\u4e0d\u78ba\u5b9a\u6642\uff0c\u70ba\u6240\u8a2d\u8a08\u7684\u7cfb\u7d71\u9810\u5148\u7559\u4e0b\u5f48\u6027\uff0c\u4ee5\u5bb9\u7d0d\u65b0\u529f\u80fd\u4ee5\u7b26\u5408\u9700\u6c42\u7684\u8b8a\u5316\uff0c\u4f46\u4e0d\u9069\u7576\u5730\u904b\u7528 design pattern\uff0c\u537b\u70ba\u8b93\u8a2d\u8a08\u7522\u751f\u4e0d\u5fc5\u8981\u7684\u8907\u96dc\u5ea6\u800c\u589e\u52a0\u958b\u767c\u7684\u8ca0\u64d4\u3002\u56e0\u6b64\uff0c\u5b78\u7fd2 design pattern \u7684\u56f0\u96e3\u4e4b\u8655\u4e26\u4e0d\u5728\u65bc design pattern \u5982\u4f55\u5be6\u4f5c\uff0c\u800c\u662f\u5728\u65bc\u5bdf\u89ba\u4f7f\u7528 design pattern \u7684\u6642\u6a5f\u3002<\/p>\n

\u5c31\u62ff\u672c\u6587\u7684\u4f8b\u5b50\u4f86\u8aaa\uff0c\u4e00\u958b\u59cb\u6211\u5011\u4e26\u4e0d\u8457\u773c\u65bc design pattern \u4e0a\uff0c\u800c\u662f\u96a8\u8457\u8a2d\u8a08\u7684\u4e0d\u540c\u8003\u91cf\u4e0a\uff0c\u85c9\u7531\u9010\u6b65\u767c\u73fe\u8207\u89e3\u6c7a\u8a2d\u8a08\u554f\u984c\u7684\u904e\u7a0b\u4e2d\uff0c\u8b93 design pattern \u8e8d\u7136\u6210\u5f62\u3002\u8b93\u554f\u984c\u4f86\u4e3b\u5c0e\u8a2d\u8a08\uff0c\u800c\u975e\u8b93\u8a2d\u8a08\u4f7f\u554f\u984c\u8907\u96dc\u5316<\/a>\u3002\u7576\u7136\uff0c\u9019\u4e5f\u6709\u8cf4\u65bc\u958b\u767c\u8005\u5728\u5e73\u5e38\u5c31\u8981\u4e0d\u65b7\u5730\u7df4\u7fd2\u8207\u601d\u8003\uff0c\u7562\u7adf\u7c21\u6f54\u800c\u5bcc\u6709\u5f48\u6027\u7684\u8a2d\u8a08\u4e0d\u662f\u4e00\u8e74\u53ef\u5e7e\u7684<\/a>\u5440\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

\u4e00\u958b\u59cb\u6211\u5011\u4e26\u4e0d\u8457\u773c\u65bc design pattern \u4e0a\uff0c\u800c\u662f\u96a8\u8457\u8a2d\u8a08\u7684\u4e0d\u540c\u8003\u91cf\u4e0a\uff0c\u85c9\u7531\u9010\u6b65\u767c\u73fe\u8207\u89e3\u6c7a\u8a2d\u8a08\u554f\u984c\u7684\u904e\u7a0b\u4e2d\uff0c\u8b93 design pattern \u8e8d\u7136\u6210\u5f62\u3002\u8b93\u554f\u984c\u4f86\u4e3b\u5c0e\u8a2d\u8a08\uff0c\u800c\u975e\u8b93\u8a2d\u8a08\u4f7f\u554f\u984c\u8907\u96dc\u5316\u3002 \u95b1\u8b80\u5168\u6587 →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29,37,19,3],"tags":[],"class_list":["post-196","post","type-post","status-publish","format-standard","hentry","category-29","category-37","category-19","category-3"],"_links":{"self":[{"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/posts\/196","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/comments?post=196"}],"version-history":[{"count":0,"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/posts\/196\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/media?parent=196"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/categories?post=196"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeparty.idv.tw\/blog\/wp-json\/wp\/v2\/tags?post=196"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}