|
1
16
17 package org.springframework.core;
18
19 import java.io.IOException  ;
20 import java.lang.reflect.Constructor ;
21 import java.lang.reflect.Method ;
22 import java.util.ArrayList ;
23
24 import org.apache.commons.logging.Log;
25 import org.apache.commons.logging.LogFactory;
26 import org.objectweb.asm.ClassReader;
27 import org.objectweb.asm.Label;
28 import org.objectweb.asm.MethodVisitor;
29 import org.objectweb.asm.Opcodes;
30 import org.objectweb.asm.Type;
31 import org.objectweb.asm.commons.EmptyVisitor;
32
33 import org.springframework.util.ClassUtils;
34
35
46 public class LocalVariableTableParameterNameDiscoverer implements ParameterNameDiscoverer {
47
48 private static Log logger = LogFactory.getLog(LocalVariableTableParameterNameDiscoverer.class);
49
50
51 public String [] getParameterNames(Method method) {
52 ParameterNameDiscoveringVisitor visitor = null;
53 try {
54 visitor = visitMethod(method);
55 if (visitor.foundTargetMember()) {
56 return visitor.getParameterNames();
57 }
58 }
59 catch (IOException ex) {
60 if (logger.isDebugEnabled()) {
63 logger.debug("IOException whilst attempting to read '.class' file for class [" +
64 method.getDeclaringClass().getName() +
65 "] - unable to determine parameter names for method: " + method,
66 ex);
67 }
68 }
69 return null;
70 }
71
72 public String [] getParameterNames(Constructor ctor) {
73 ParameterNameDiscoveringVisitor visitor = null;
74 try {
75 visitor = visitConstructor(ctor);
76 if (visitor.foundTargetMember()) {
77 return visitor.getParameterNames();
78 }
79 }
80 catch (IOException ex) {
81 if (logger.isDebugEnabled()) {
84 logger.debug("IOException whilst attempting to read '.class' file for class [" +
85 ctor.getDeclaringClass().getName() +
86 "] - unable to determine parameter names for constructor: " + ctor,
87 ex);
88 }
89 }
90 return null;
91 }
92
93
96 private ParameterNameDiscoveringVisitor visitMethod(Method method) throws IOException {
97 ClassReader classReader = createClassReader(method.getDeclaringClass());
98 FindMethodParameterNamesClassVisitor classVisitor = new FindMethodParameterNamesClassVisitor(method);
99 classReader.accept(classVisitor, false);
100 return classVisitor;
101 }
102
103
106 private ParameterNameDiscoveringVisitor visitConstructor(Constructor ctor) throws IOException {
107 ClassReader classReader = createClassReader(ctor.getDeclaringClass());
108 FindConstructorParameterNamesClassVisitor classVisitor = new FindConstructorParameterNamesClassVisitor(ctor);
109 classReader.accept(classVisitor, false);
110 return classVisitor;
111 }
112
113
116 private ClassReader createClassReader(Class clazz) throws IOException {
117 return new ClassReader(clazz.getResourceAsStream(ClassUtils.getClassFileName(clazz)));
118 }
119
120
121
125 private static abstract class ParameterNameDiscoveringVisitor extends EmptyVisitor {
126
127 private String methodNameToMatch;
128
129 private String descriptorToMatch;
130
131 private int numParamsExpected;
132
133 private boolean foundTargetMember = false;
134
135 private String [] parameterNames;
136
137 public ParameterNameDiscoveringVisitor(String name,int numParams) {
138 this.methodNameToMatch = name;
139 this.numParamsExpected = numParams;
140 }
141
142 public void setDescriptorToMatch(String descriptor) {
143 this.descriptorToMatch = descriptor;
144 }
145
146 public MethodVisitor visitMethod(int access, String name, String desc, String signature, String [] exceptions) {
147 if (name.equals(this.methodNameToMatch) &&
148 desc.equals(this.descriptorToMatch)) {
149 this.foundTargetMember = true;
150 return new LocalVariableTableVisitor(isStatic(access), this,this.numParamsExpected);
151 }
152 else {
153 return null;
155 }
156 }
157
158 private boolean isStatic(int access) {
159 return ((access & Opcodes.ACC_STATIC) > 0);
160 }
161
162 public boolean foundTargetMember() {
163 return this.foundTargetMember;
164 }
165
166 public String [] getParameterNames() {
167 if (!foundTargetMember()) {
168 throw new IllegalStateException ("Can't ask for parameter names when target member has not been found");
169 }
170
171 return this.parameterNames;
172 }
173
174 public void setParameterNames(String [] names) {
175 this.parameterNames = names;
176 }
177 }
178
179
180 private static class FindMethodParameterNamesClassVisitor extends ParameterNameDiscoveringVisitor {
181
182 public FindMethodParameterNamesClassVisitor(Method method) {
183 super(method.getName(),method.getParameterTypes().length);
184 setDescriptorToMatch(Type.getMethodDescriptor(method));
185 }
186 }
187
188
189 private static class FindConstructorParameterNamesClassVisitor extends ParameterNameDiscoveringVisitor {
190
191 public FindConstructorParameterNamesClassVisitor(Constructor cons) {
192 super("<init>",cons.getParameterTypes().length);
193 Type[] pTypes = new Type[cons.getParameterTypes().length];
194 for (int i = 0; i < pTypes.length; i++) {
195 pTypes[i] = Type.getType(cons.getParameterTypes()[i]);
196 }
197 setDescriptorToMatch(Type.getMethodDescriptor(Type.VOID_TYPE,pTypes));
198 }
199 }
200
201
202 private static class LocalVariableTableVisitor extends EmptyVisitor {
203
204 private boolean isStatic;
205
206 private ParameterNameDiscoveringVisitor memberVisitor;
207
208 private int numParameters;
209
210 private ArrayList parameterNames;
211
212 private boolean hasLVTInfo = false;
213
214 public LocalVariableTableVisitor(boolean isStatic, ParameterNameDiscoveringVisitor memberVisitor, int numParams) {
215 this.isStatic = isStatic;
216 this.numParameters = numParams;
217 this.parameterNames = new ArrayList (this.numParameters);
218 this.memberVisitor = memberVisitor;
219 }
220
221 public void visitLocalVariable(String name, String description, String signature, Label start, Label end, int index) {
222 this.hasLVTInfo = true;
223 if (!this.isStatic) {
224 index--;
225 }
226 if (index >= 0 && (this.parameterNames.size() < this.numParameters)) {
227 this.parameterNames.add(name);
228 }
229 }
230
231 public void visitEnd() {
232 if (this.hasLVTInfo || this.isStatic && numParameters == 0) {
233
239 String [] names = new String [this.parameterNames.size()];
240 names = (String []) this.parameterNames.toArray(names);
241 this.memberVisitor.setParameterNames(names);
242 }
243 }
244 }
245
246 }
247 |
Popular Tags |
Java API By Example, From Geeks To Geeks.