Assertion
Assertion is a logical judgment used to check that something should not happen
The Assert keyword was introduced in JDK1.4 and can be enabled through the JVM parameter -enableassertions
Assert assertion tool class is provided in SpringBoot, which is usually used for data legality check
// It is required that the parameter object must be non-null (Not Null), otherwise an exception will be thrown and the release will not be allowed // Parameters The message parameter is used to customize the exception message. void notNull(Object object, String message) // It is required that the parameter must be empty (Null), otherwise an exception will be thrown, and it will not be "released". // Contrary to the notNull() method assertion rules void isNull(Object object, String message) // The parameter must be true (True), otherwise an exception will be thrown, and it will not be "released". void isTrue(boolean expression, String message) // It is required that the parameter (List/Set) must be non-empty (Not Empty), otherwise an exception will be thrown and will not be released void notEmpty(Collection collection, String message) // It is required that the parameter (String) must have a length (ie, Not Empty), otherwise an exception will be thrown and no release will be made void hasLength(String text, String message) // It is required that the parameter (String) must have content (that is, Not Blank), otherwise an exception will be thrown and the release will not be allowed void hasText(String text, String message) // The parameter is required to be an instance of the specified type, otherwise an exception will be thrown and no release will be made void isInstanceOf(Class type, Object obj, String message) // It is required that the parameter `subType` must be a subclass or implementation class of the parameter superType, otherwise an exception will be thrown and will not be released void isAssignable(Class superType, Class subType, String message)
Object, array, collection
ObjectUtils
Get basic information about an object
// Get the class name of the object. When the parameter is null, return the string: "null" String nullSafeClassName(Object obj) // When the parameter is null, return 0 int nullSafeHashCode(Object object) // When the parameter is null, return the string: "null" String nullSafeToString(boolean[] array) // Get the object HashCode (string in hexadecimal form). Returns 0 when the argument is null String getIdentityHexString(Object obj) // Get the class name and HashCode of the object. When the parameter is null, returns a string: "" String identityToString(Object obj) // Equivalent to the toString() method, but when the parameter is null, return a string: "" String getDisplayString(Object obj)
judgment tool
//Check if the array is empty
boolean isEmpty(Object[] array)
// Determine whether the parameter object is an array
boolean isArray(Object obj)
// Check if the array contains the specified element
boolean containsElement(Object[] array, Object element)
// equal, or both are null, return true
boolean nullSafeEquals(Object o1, Object o2)
/*
To judge whether the parameter object is empty, the judgment standard is:
Optional: Optional. empty()
Array: length == 0
CharSequence: length == 0
Collection: Collection.isEmpty()
Map: Map.isEmpty()
*/
boolean isEmpty(Object obj)
Other tools and methods
// Append new elements to the end of the parameter array and return a new array <A, O extends A> A[] addObjectToArray(A[] array, O obj) // Array of native basic types --> Array of wrapper classes Object[] toObjectArray(Object source)
StringUtils
String Judgment Tool
// Determine whether the string is null, or "". Note that a string containing whitespace is not empty boolean isEmpty(Object str) // Determine whether the string ends with the specified content. ignore case boolean endsWithIgnoreCase(String str, String suffix) // Determine whether the string starts with the specified content. ignore case boolean startsWithIgnoreCase(String str, String prefix) // Whether to include whitespace boolean containsWhitespace(String str) // Determine whether the string is not empty and the length is not 0, that is, Not Empty boolean hasLength(CharSequence str) // Determine whether the string contains actual content, that is, not only blanks, that is, Not Blank boolean hasText(CharSequence str) // Determine whether the specified index of the string contains a substring. boolean substringMatch(CharSequence str, int index, CharSequence substring) // Count the number of occurrences of a specified substring in a string int countOccurrencesOf(String str, String sub)
string manipulation tools
// Find and replace the specified substring String replace(String inString, String oldPattern, String newPattern) // Remove specific characters at the end String trimTrailingCharacter(String str, char trailingCharacter) // Remove specific characters from the header String trimLeadingCharacter(String str, char leadingCharacter) // remove leading whitespace String trimLeadingWhitespace(String str) // remove leading whitespace String trimTrailingWhitespace(String str) // remove leading and trailing whitespace String trimWhitespace(String str) // remove leading, trailing and intermediate whitespace String trimAllWhitespace(String str) // delete the specified substring String delete(String inString, String pattern) // Delete specified characters (can be multiple) String deleteAny(String inString, String charsToDelete) // Execute the trim() method on each item of the array String[] trimArrayElements(String[] array) // Decode the URL string String uriDecode(String source, Charset charset)
Path-relative tool methods
// Parse the path string and optimize the ".." String cleanPath(String path) // Parse the path string and parse out the file name part String getFilename(String path) // Parse the path string and parse out the file extension String getFilenameExtension(String path) // Compare two strings to determine whether they are the same path. ".." in the path is automatically handled boolean pathEquals(String path1, String path2) // Remove the suffix part of the file path name String stripFilenameExtension(String path) // Use ". as a delimiter to get the last part String unqualify(String qualifiedName) // Use the specified character as a delimiter to get the last part String unqualify(String qualifiedName, char separator)
CollectionUtils
Collection Judgment Tool
// Determine whether the List/Set is empty boolean isEmpty(Collection<?> collection) // Check if the Map is empty boolean isEmpty(Map<?,?> map) // Determine whether an object is contained in the List/Set boolean containsInstance(Collection<?> collection, Object element) // Determine whether an object is contained in the List/Set by means of an iterator boolean contains(Iterator<?> iterator, Object element) // Determine if the List/Set contains any of some objects boolean containsAny(Collection<?> source, Collection<?> candidates) // Determine whether each element in the List/Set is unique. That is, there are no duplicate elements in the List/Set boolean hasUniqueObject(Collection<?> collection)
collection manipulation tools
// Add all elements in Array to List/Set <E> void mergeArrayIntoCollection(Object array, Collection<E> collection) // Add the key-value pairs in Properties to the Map <K,V> void mergePropertiesIntoMap(Properties props, Map<K,V> map) // Return the last element in the List <T> T lastElement(List<T> list) // Return the last element in the Set <T> T lastElement(Set<T> set) // returns the first element of the parameter candidates that exists in the parameter source <E> E findFirstMatch(Collection<?> source, Collection<E> candidates) // Returns an element of the specified type in the List/Set. <T> T findValueOfType(Collection<?> collection, Class<T> type) // Returns an element of the specified type in the List/Set. If the first type is not found, look for the second type, and so on Object findValueOfType(Collection<?> collection, Class<?>[] types) // return the type of the elements in the List/Set Class<?> findCommonElementType(Collection<?> collection)
Files, resources, IO streams
FileCopyUtils
enter
// read from the file into the byte array byte[] copyToByteArray(File in) // read from input stream into byte array byte[] copyToByteArray(InputStream in) // read from the input stream into a string String copyToString(Reader in)
output
// From byte array to file void copy(byte[] in, File out) // from file to file int copy(File in, File out) // from byte array to output stream void copy(byte[] in, OutputStream out) // from input stream to output stream int copy(InputStream in, OutputStream out) // from input stream to output stream int copy(Reader in, Writer out) // from string to output stream void copy(String in, Writer out)
ResourceUtils
Get file from resource path
// Determine whether the string is a valid URL string. static boolean isUrl(String resourceLocation) // get the URL static URL getURL(String resourceLocation) // Get the file (it cannot be used normally in the JAR package, it needs to be an independent file) static File getFile(String resourceLocation)
Resource
// file system resource D:\... FileSystemResource // URL resources such as file://... http://... UrlResource // Resources under the classpath, classpth:... ClassPathResource // Resources in the context of the web container (jar package, war package) ServletContextResource
// Determine whether the resource exists boolean exists() // Get the File object from the resource File getFile() // get the URI object from the resource URI getURI() // get the URI object from the resource URL getURL() // Get the InputStream of the resource InputStream getInputStream() // Get the description information of the resource String getDescription()
StreamUtils
enter
void copy(byte[] in, OutputStream out) int copy(InputStream in, OutputStream out) void copy(String in, Charset charset, OutputStream out) long copyRange(InputStream in, OutputStream out, long start, long end)
output
byte[] copyToByteArray(InputStream in) String copyToString(InputStream in, Charset charset) // Discard the contents of the input stream int drain(InputStream in)
Reflection, AOP
ReflectionUtils
access method
// Find the specified method in the class Method findMethod(Class<?> clazz, String name) // Same as above, additionally provide method parameter type as search condition Method findMethod(Class<?> clazz, String name, Class<?>... paramTypes) // Get all methods in the class, including inherited ones Method[] getAllDeclaredMethods(Class<?> leafClass) // Find the specified constructor in the class Constructor<T> accessibleConstructor(Class<T> clazz, Class<?>... parameterTypes) // Whether it is the equals() method boolean isEqualsMethod(Method method) // Whether it is the hashCode() method boolean isHashCodeMethod(Method method) // Is it the toString() method boolean isToStringMethod(Method method) // Whether it is a method inherited from the Object class boolean isObjectMethod(Method method) // Check if a method declares to throw the specified exception boolean declaresException(Method method, Class<?> exceptionType)
execution method
// Execution method Object invokeMethod(Method method, Object target) // Same as above, provide method parameters Object invokeMethod(Method method, Object target, Object... args) // Cancel the Java permission check. for subsequent execution of the private method void makeAccessible(Method method) // Cancel the Java permission check. for subsequent execution of the private constructor void makeAccessible(Constructor<?> ctor)
get fields
// Find the specified attribute in the class Field findField(Class<?> clazz, String name) // Same as above, more types of attributes are provided Field findField(Class<?> clazz, String name, Class<?> type) // Is it a "public static final" property boolean isPublicStaticFinal(Field field)
set field
// Get the field attribute value of the target object
Object getField(Field field, Object target)
// Set the field attribute value of the target object, the value is value
void setField(Field field, Object target, Object value)
// Equivalent assignment of properties of similar objects
void shallowCopyFieldState(Object src, Object dest)
// Cancel Java's permission control check. For subsequent reading and writing of the private property
void makeAccessible(Field field)
// Execute callback for each property of the class
void doWithFields(Class<?> clazz, ReflectionUtils. FieldCallback fc)
// As above, there is an additional attribute filtering function.
void doWithFields(Class<?> clazz, ReflectionUtils. FieldCallback fc,
ReflectionUtils. FieldFilter ff)
// Same as above, but excluding inherited properties
void doWithLocalFields(Class<?> clazz, ReflectionUtils. FieldCallback fc)
AopUtils
Judging the agent type
// Determine whether it is a Spring proxy object boolean isAopProxy() // Determine whether it is a jdk dynamic proxy object isJdkDynamicProxy() // Determine whether it is a CGLIB proxy object boolean isCglibProxy()
Get the class of the proxy object
// Get the target class to be proxied Class<?> getTargetClass()
AopContext
Get the proxy object of the current object
Object currentProxy
Thanks for reading, I hope it can help you 🙂
Source: juejin.cn/post/7043403364020781064
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