http断点续传简单实现（java)

/* '<>pz<c  
**SiteFileFetch.java UR1U; k  
*/ 7AV!v`  
package NetFox; RA>xol~xy  
import java.io.*; T1M4@j  
import java.net.*; opte)=]J  
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public class SiteFileFetch extends Thread { <3O>  
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SiteInfoBean siteInfoBean = null; //文件信息Bean k/j]*~"
 
long[] nStartPos; //开始位置 UXDd
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long[] nEndPos; //结束位置 zK k;&y|{  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 T.`EDluG  
long nFileLength; //文件长度 DFVaZN?~  
boolean bFirst = true; //是否第一次取文件 u~bk~3.I  
boolean bStop = false; //停止标志 $ze%!C  
File tmpFile; //文件下载的临时信息 flR6^6E  
DataOutputStream output; //输出到文件的输出流 Br`Xw^S  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） A%k@75V@  
public SiteFileFetch(SiteInfoBean bean) throws IOException  zy  
{ $FNj>1  
siteInfoBean = bean; 8}XtVF;  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Z8z.Xn  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); Wf-i)oc4I  
if(tmpFile.exists ()) 9K@`n:Rw  
{ ;&s`g   
bFirst = false; ?E^~z-  
read_nPos();  pzg|?U  
} ,gUSW  
else i`z1if6O  
{ ;v^tUyhCb  
nStartPos = new long[bean.getNSplitter()]; i!*w'[G->Y  
nEndPos = new long[bean.getNSplitter()]; q}*(rR9/Br  
} jdK~]eld=  
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} /$|
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public void run() z4HIDb  
{ eY-W
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//获得文件长度 Xjw>Qws  
//分割文件 d/v{I  
//实例FileSplitterFetch SGXXv  
//启动FileSplitterFetch线程 f<=<:+  
//等待子线程返回 S*Qip,u  
try{ A0m  
if(bFirst) :"5
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{ n!2"pRIi  
nFileLength = getFileSize(); 3%bCv_6B  
if(nFileLength == -1) )M<"YI)g  
{ -+A
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System.err.println("File Length is not known!"); g j8rrd|  
} ({v$!AAv  
else if(nFileLength == -2) E/v.+m  
{ ai)S:2  
System.err.println("File is not access!"); "9'~
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} uUB,OmLN  
else B8F.}M-!  
{ )a AKO`  
for(int i=0;i<nStartPos.length;i++) ~Z9Eb|B  
{ \T`InBbf  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); cfBq/2I  
} ^I4'7]n-  
for(int i=0;i<nEndPos.length-1;i++) A'vQtlvKA  
{ Jz&a9  
nEndPos = nStartPos[i+1]; Cc/h|4  
} ,m;S-Im_Xr  
nEndPos[nEndPos.length-1] = nFileLength; Jr$,w7tQn@  
} PIR#M('  
} VG0Ty;bV  
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//启动子线程 <o@&I " o  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; ajC'C!"^Ty  
for(int i=0;i<nStartPos.length;i++) D99g}  
{ YT'G#U1x~  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), gqV66xmJ3  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), H=Scrvfx  
nStartPos,nEndPos,i); UF0W%Z  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 6_]-&&Nr  
fileSplitterFetch.start(); 4Vl_vTz{i  
} eG&\b-%  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), d3-F?i 5d  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); *`2.WF@E)  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", =lT~  
nEndPos = " + nFileLength); HK&Ul=^VN|  
// fileSplitterFetch[nPos.length-1].start(); .B?6  
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//等待子线程结束 Fa<>2KkOr  
//int count = 0; W!vN(1:(  
//是否结束while循环 wNo2$>*  
boolean breakWhile = false; uu ahR  
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while(!bStop) [Jv0^"]  
{ "yaz!?O>  
write_nPos(); OAJGwm  
Utility.sleep(500); rQmDpoy
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breakWhile = true; Y-!~x0-H  
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for(int i=0;i<nStartPos.length;i++) $J6Pv   
{ PD #9Z=Hj  
if(!fileSplitterFetch.bDownOver) Dl=9<:6FW  
{ =
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breakWhile = false; KaVNRS  
break; DJ_[{WAV  
} 9 5bi W  
} b-?wJSf|  
if(breakWhile) eS#kDa/ %  
break; $HgBzZ7A2  
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//count++; {1?94rz  
//if(count>4) U*sjv6*T  
// siteStop(); w`BY>Xft0
 
} Kny0 (  
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System.err.println("文件下载结束！"); L& =a(  
} }9:(l  
catch(Exception e){e.printStackTrace ();} o;'E("!<Z  
} S]!s)q-- z  
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//获得文件长度 ga?:k,xv  
public long getFileSize() f(M$m,d  
{ l5h+:^#M5c  
int nFileLength = -1; X,5}i5'!  
try{ Z2n Jw  
URL url = new URL(siteInfoBean.getSSiteURL()); k+9*7y8w  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); /q|r!+  
httpConnection.setRequestProperty("User-Agent","NetFox"); `wI$  

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F}
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int responseCode=httpConnection.getResponseCode(); k1lo{jw`  
if(responseCode>=400) 5Zf^cou  
{ :1*q}R   
processErrorCode(responseCode); 5D]3I=kj  
return -2; //-2 represent access is error ak,KHA6u  
} ( p(/  
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String sHeader; gB _/(  
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for(int i=1;;i++) J.EBt3  
{ 4nsc`Hu  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); ]ilQq~X  
//Utility.log(in.readLine()); ^fiJxU  
sHeader=httpConnection.getHeaderFieldKey(i); (rmOv\hG9V  
if(sHeader!=null) V0)bPcS/  
{ "Jahc.I  
if(sHeader.equals("Content-Length")) ,NO2{Ha$  
{ qt(+X  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); Hs:0j$  
break; 1d$qr`  
} ?"F9~vx&G  
} !dQmg'_V  
else  =oE(ur  
break; N#``(a  
} noNJ+0S  
} reQr=OAez  
catch(IOException e){e.printStackTrace ();} sYEh>%mo^C  
catch(Exception e){e.printStackTrace ();} 8Y]% S9.  
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Utility.log(nFileLength); Iuyq!R4:7  
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return nFileLength; d*YVk{s7V  
} ')
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8  
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//保存下载信息（文件指针位置） v9\U2j  
private void write_nPos() Ucx"\/"  
{ 9 NGKh3V  
try{ U{\9mt7b!  
output = new DataOutputStream(new FileOutputStream(tmpFile)); r>e1IG  
output.writeInt(nStartPos.length); $7QGi|W*k  
for(int i=0;i<nStartPos.length;i++) q+znb'i-x  
{ 8(Cs<C!  
// output.writeLong(nPos); /[=Yv!  
output.writeLong(fileSplitterFetch.nStartPos); .@Lktc  
output.writeLong(fileSplitterFetch.nEndPos); uTdx`>M,O  
} yhkKakg,)  
output.close(); o;9 G{Xj3@  
} _/czH<   
catch(IOException e){e.printStackTrace ();} sYq:2Wn>8Q  
catch(Exception e){e.printStackTrace ();} yV~TfTJ  
} A`--*$8\  
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Dm
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//读取保存的下载信息（文件指针位置） Z0/$XS9|h;  
private void read_nPos() CnpQdI  
{ fsl ZJE  
try{ PNo9.-@G  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ^e]O-,UBk  
int nCount = input.readInt(); qeW.
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nStartPos = new long[nCount]; EI9;J-c  
nEndPos = new long[nCount]; Pn,>eD*g  
for(int i=0;i<nStartPos.length;i++) hj=qWGRgI  
{ f\rE{%  
nStartPos = input.readLong(); ;reBJk  
nEndPos = input.readLong(); k:&vW21E  
} soRYM  
input.close(); n$lVmQ6  
} z~-(nyaBS  
catch(IOException e){e.printStackTrace ();} cL<,]%SkE  
catch(Exception e){e.printStackTrace ();} X }`
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} xnC:?d  
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private void processErrorCode(int nErrorCode) b^
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{ YQ@2p?4m  
System.err.println("Error Code : " + nErrorCode); h<Ct[46,S  
} ? 'qyI^m@  
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//停止文件下载 S0Ur{!9\#^  
public void siteStop() B^!-%_q  
{ -e_
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bStop = true; QH,Fw$1  
for(int i=0;i<nStartPos.length;i++) x=Aq5*A0  
fileSplitterFetch.splitterStop(); Kx?.g#>U;  
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} k*u6'IKi.4  
} \#PZZ
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//负责部分文件的抓取 YV _ 7 .+A  
**FileSplitterFetch.java &"?99E>  
*/ =it@U/  
package NetFox; l1#.rg  
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import java.io.*; JljCI@  
import java.net.*; 2">de/jS  
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public class FileSplitterFetch extends Thread { :.tL~% q  
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String sURL; //File URL |g>
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long nStartPos; //File Snippet Start Position )+"5($~  
long nEndPos; //File Snippet End Position n=PfV3B  
int nThreadID; //Thread's ID u(fZ^  
boolean bDownOver = false; //Downing is over u|Oc+qA(  
boolean bStop = false; //Stop identical C(9"59>{]y  
FileAccessI fileAccessI = null; //File Access interface P^# 4m  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException D)bL;h  
{ xFekSH7[F  
this.sURL = sURL; 6O/c%1VHA3  
this.nStartPos = nStart; )Fp$ *]|  
this.nEndPos = nEnd; S8B?uU  
nThreadID = id; ?E_;[(Mcr  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 nbB*d@"  
} "G-h8IN^O  
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public void run() 98)C 7N'  
{ MRw4?HqB  
while(nStartPos < nEndPos && !bStop) ?:M4GY"gV  
{ :h |]j[2p  
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try{ p!~1~q
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URL url = new URL(sURL); ZDAW>H<  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ).IyjHY  
httpConnection.setRequestProperty("User-Agent","NetFox");
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String sProperty = "bytes="+nStartPos+"-"; 8MI8~
 
httpConnection.setRequestProperty("RANGE",sProperty); uO-|?{29  
Utility.log(sProperty); c_C
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InputStream input = httpConnection.getInputStream(); $=Ns7Sbup  
//logResponseHead(httpConnection); @tPr\F  
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byte[] b = new byte[1024]; =E>P,"D  
int nRead; zfE8=d8U  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) >MKj~Ud  
{ k0O5c[j  
nStartPos += fileAccessI.write(b,0,nRead); ^-Ygh[x  
//if(nThreadID == 1) _yUYEq<`  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); S6_:\Q  
} *Ti"8^`6  
]j>`BK>FE  
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Utility.log("Thread " + nThreadID + " is over!"); W8$0y2  
bDownOver = true; 122s7A  
//nPos = fileAccessI.write (b,0,nRead); JBLUX,  
} <&3aP}  
catch(Exception e){e.printStackTrace ();} ez!W0  
} ^H7xFd|>  
} -|^)8  
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//打印回应的头信息 i\l}M]Z#  
public void logResponseHead(HttpURLConnection con) <G|
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{ HzKY2F(,  
for(int i=1;;i++) :fwtPvLo  
{ ze
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String header=con.getHeaderFieldKey(i); K6 >\4'q  
if(header!=null) 0}qlZFB  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); 09anQHa  
Utility.log(header+" : "+con.getHeaderField(header)); \lm]G7h  
else @tY]=pqn_  
break; 'fGKRd|)  
} UOf\pG  
} 7n.Oem  
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public void splitterStop() V" 8 G-dK  
{ Eyjsbj8  
bStop = true; nDXEm6|e  
} qbeUc5`1  
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} {+7FBdxVB  
}.&;NgZS  
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/* M-@X&bm,S  
**FileAccess.java
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*//文件访问(定位，写) |%F,n2  
package NetFox; ]uypi#[  
import java.io.*; pvUV5^B(M  
.,p=e$x]  
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public class FileAccessI implements Serializable{ ZK'46lh  
prN+{N8YC  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 Ikf[K%NKn  
RandomAccessFile oSavedFile; w-# f^#  
long nPos; L;$>SLl,  
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*j&)=8Y|   
public FileAccessI() throws IOException ^}p##7t[  
{ Z:7eroZP  
this("",0); B+U:=591  
} WEe7\bWF  
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public FileAccessI(String sName,long nPos) throws IOException [bP^RY:  
{ eBnx$  
oSavedFile = new RandomAccessFile(sName,"rw"); tx>7?e8E  
this.nPos = nPos; E5)0YYjHZ  
oSavedFile.seek(nPos); >FwK_Zd'  
} |r Aot2  
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public synchronized int write(byte[] b,int nStart,int nLen) t~j6wsx;  
{ \q1tT!]  
int n = -1; {~F|"v  
try{ HrvyI)4{  
oSavedFile.write(b,nStart,nLen); }URdoTOvb  
n = nLen; EG3,TuDH8  
} Rh|9F yN  
catch(IOException e) -Q@f),  
{ %eg+.  
e.printStackTrace (); S\8v)|Pr  
} O8$~dzf,2  
|*NZ^6`@  
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return n; vJ65F6=G  
} }-Mg&~e`  
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} M@.S Q@E  
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/* :,JaOn'  
**SiteInfoBean.java r9_ ON|  
*/ H u;"TG  
package NetFox; 5U475&  
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public class SiteInfoBean { B~KxUp  
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private String sSiteURL; //Site's URL gA(npsUHI  
private String sFilePath; //Saved File's Path 3E|||3rf  
private String sFileName; //Saved File's Name ]LC4rS  
private int nSplitter; //Count of Splited Downloading File  9BtGzI\  
2L4[~>  
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public SiteInfoBean() 7_1 Iadb  
{//nSplitter的缺省值为5 Z
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//default value of nSplitter is 5 7y|U!r"Y  
this("","","",5); .A< HM}   
} ['}|#
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) VAL? Z  
{ L[2qCxB'^  
sSiteURL= sURL; CqnHh@]nu  
sFilePath = sPath; / 3N2?zS{  
sFileName = sName; k={D!4kKz  
this.nSplitter = nSpiltter; U7x  
7p.8{zQ*  
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} 'r!!W0-K  
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public String getSSiteURL() XS&Pc  
{ {A0F/#M]  
return sSiteURL; fxcE1=a  
} _;PQt" ]  
$Lstq_x+  
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public void setSSiteURL(String value) o
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{ m-O*t$6  
sSiteURL = value; F7=9> ,  
} D=a*Xu2zq  
)W\)kDh!  
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public String getSFilePath() nr]=O`Mvh  
{ Hj >fg2/  
return sFilePath; i<Ms2^  
} [s^pP2  
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public void setSFilePath(String value) a^&"gGg  
{ OG<*&V  
sFilePath = value; aZ~e;}w.Zq  
} c_
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X{#^O/  
ph6/+[:  
public String getSFileName() l^R:W#*+U  
{ my sXgS&S  
return sFileName; xCL)<8[R,}  
} l#cVQ_^"  
On);SN'  
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public void setSFileName(String value) *=@8t^fa86  
{ ?3N/
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sFileName = value; aN"
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} *P *.'XM  
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public int getNSplitter() z&!o1uq  
{ _~Od G  
return nSplitter; \KJTR0EB:>  
} $]?pAqU\  
;0_T\{H"nR  
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public void setNSplitter(int nCount) 9hK8dJw  
{ L`M{bRl+1  
nSplitter = nCount; {C`M<2W]  
} mu0L_u(P  
} \Yp"D7:Qi  
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/* 5Qg*j/z
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**Utility.java 71Q`B#t0'Z  
*/ T\zn&6  
package NetFox; d+P<ce2G  
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public class Utility { jY9tq[~/  
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public Utility() s!0
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{ r_ 9"^Er  
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;,/G*`81B  
} 5-a^Frmg#"  
mMZ=9 ?m  
//线程睡眠 f3,Xb ]h  
public static void sleep(int nSecond) k"dE?v\cG  
{ iw(`7(*  
try{ \8Ewl|"N:u  
Thread.sleep(nSecond); V'.gE6we  
} Rp zuSh  
catch(Exception e) HE4S%#bH>  
{ t- //.  
e.printStackTrace (); bMqS:+  
} |Qpo[E}a  
} I`{=[.c  
' z^v
}~  
//日志 ,=ju^_^sA  
public static void log(String sMsg) Odt<WG  
{ ]~m=b
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System.err.println(sMsg); m&*0<N  
} UBwYwm0  
3wgZDF38  
T2T?)_f /  
public static void log(int sMsg) W.7u6F`  
{ h1j1PRE  
System.err.println(sMsg); u7wZPIC{_  
} } F*=+n  
} IxlPpS9Wx  
R;/LB^X]  
2zjY|g/  
/* \<=.J`o{  
**TestMethod.java HRd02tah  
*/ :OaGdL   
package NetFox; ]_y;Igaj  
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public class TestMethod { h=cA]^:=  
a'G[!"  
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public TestMethod() d/?0xLW  
{ ///xx/weblogic60b2_win.exe K!88 Nox(  
try{ WdrMp  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); B8-Y)u1G  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); MIv,$  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 2IDn4<`  
fileFetch.start(); 6`'KM/  
} \cAifU  
catch(Exception e){e.printStackTrace ();} ,+g0#8?p^x  
#4sSt-s&  
^[ >  
} >F!X'#Iv  
~;uW) [  
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public static void main(String[] args) X`}4=>  
{ X0m6<q  
new TestMethod(); wB*}XJah  
} M<)Vtn  
} IC.R4-  
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