Spring dependency injection Principle Analysis, spring Injection Analysis

Spring dependency injection Principle Analysis, spring Injection Analysis

PropertyDefinition. java

1 package junit. test; 2 3 public class PropertyDefinition {4 private String name; 5 private String ref; 6 7 public PropertyDefinition (String name, String ref) {8 this. name = name; 9 this. ref = ref; 10} 11 12 public String getName () {13 return name; 14} 15 public void setName (String name) {16 this. name = name; 17} 18 public String getRef () {19 return ref; 20} 21 public void setRef (String ref) {22 this. ref = ref; 23} 24 25}PropertyDefinition

BeanDefinition. java

1 package junit. test; 2 3 import java. util. arrayList; 4 import java. util. list; 5 6 public class BeanDefinition {7 private String id; 8 private String className; 9 private List <PropertyDefinition> propertys = new ArrayList <PropertyDefinition> (); 10 11 public BeanDefinition (String id, String className) {12 this. id = id; 13 this. className = className; 14} 15 public String getId () {16 return id; 17} 18 public void setId (String id) {19 this. id = id; 20} 21 public String getClassName () {22 return className; 23} 24 public void setClassName (String className) {25 this. className = className; 26} 27 public List <PropertyDefinition> getPropertys () {28 return propertys; 29} 30 public void setPropertys (List <PropertyDefinition> propertys) {31 this. propertys = propertys; 32} 33 34}BeanDefinition

ItcastClassPathXMLApplicationContext. java

Package junit. test; import java. beans. introspectionException; import java. beans. introspector; import java. beans. propertyDescriptor; import java. lang. reflect. method; import java.net. URL; import java. util. arrayList; import java. util. hashMap; import java. util. hashSet; import java. util. list; import java. util. map; import org. dom4j. document; import org. dom4j. element; import org. dom4j. XPath; import org. dom4j. io. SAXRead Er;/*** Chuan Zhi Chuan ke edition container **/public class a {private List <BeanDefinition> beanDefines = new ArrayList <BeanDefinition> (); private Map <String, object> sigletons = new HashMap <String, Object> (); public ItcastClassPathXMLApplicationContext (String filename) {this. readXML (filename); this. instanceBeans (); this. injectObject ();}/*** is the bean Object Property injection value */private void injectObject () {for (BeanDefinition beanDefiniti On: beanDefines) {Object bean = sigletons. get (beanDefinition. getId (); if (bean! = Null) {try {PropertyDescriptor [] ps = Introspector. getBeanInfo (bean. getClass ()). getPropertyDescriptors (); for (PropertyDefinition propertyDefinition: beanDefinition. getPropertys () {for (PropertyDescriptor properdesc: ps) {if (propertyDefinition. getName (). equals (properdesc. getName () {Method setter = properdesc. getWriteMethod (); // setter method for obtaining attributes, private if (setter! = Null) {Object value = sigletons. get (propertyDefinition. getRef (); setter. setAccessible (true); setter. invoke (bean, value); // inject the referenced object into the attribute} break ;}}} catch (Exception e) {}}}/*** instantiate bean */private void instanceBeans () {for (BeanDefinition beanDefinition: beanDefines) {try {if (beanDefinition. getClassName ()! = Null &&! "". Equals (beanDefinition. getClassName (). trim () sigletons. put (beanDefinition. getId (), Class. forName (beanDefinition. getClassName ()). newInstance ();} catch (Exception e) {e. printStackTrace () ;}}/ *** read xml configuration file * @ param filename */private void readXML (String filename) {SAXReader saxReader = new SAXReader (); document document = null; try {URL xmlpath = this. getClass (). getClassLoader (). getResource (filename); document = saxReader. read (xmlpath); Map <String, String> nsMap = new HashMap <String, String> (); nsMap. put ("ns", "http://www.springframework.org/schema/beans"); // Add the namespace XPath xsub = document. createXPath ("// ns: beans/ns: bean"); // create the beans/bean query path xsub. setNamespaceURIs (nsMap); // set the namespace List <Element> beans = xsub. selectNodes (document); // obtain all bean nodes under the document for (Element element: beans) {String id = element. attributeValue ("id"); // obtain the id attribute value String clazz = element. attributeValue ("class"); // get the class attribute value BeanDefinition beanDefine = new BeanDefinition (id, clazz); XPath propertysub = element. createXPath ("ns: property"); propertysub. setNamespaceURIs (nsMap); // set the namespace List <Element> propertys = propertysub. selectNodes (element); for (Element property: propertys) {String propertyName = property. attributeValue ("name"); String propertyref = property. attributeValue ("ref"); PropertyDefinition propertyDefinition = new PropertyDefinition (propertyName, propertyref); beanDefine. getPropertys (). add (propertyDefinition);} beanDefines. add (beanDefine) ;}} catch (Exception e) {e. printStackTrace () ;}}/*** get bean instance * @ param beanName * @ return */public Object getBean (String beanName) {return this. sigletons. get (beanName );}}ItcastClassPathXMLApplicationContext